# MCQ of Physics CUET | Common University Entrance Test |

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MCQ of Physics CUET | Common University Entrance Test |

#### MCQ of Electric Charges and Fields

Question 1: What happens when a point charge is kept at the center of a insulated metallic spherical shell?

1. Electric field outside the sphere is zero
2. Electric potential inside the sphere is zero
3. Net induced charge on the sphere is zero
4. Electric field inside the sphere is zero

Answer: D ( Electric field inside the sphere is zero )

Question 2: Two charges of equal magnitudes and separated by a  distance r exert a force F on each other. If the charges are halved and distance between them is doubled, then the  new force acting on each charge will be

1. F / 16
2. F / 4
3. 4 F
4. F / 16

Answer: A ( F / 16)

Question 3: The cause of quantization of electric charge is

1. Transfer of electrons
2. Transfer of protons
3. Transfer of integral number of electrons
4. None of the above

Answer: C (Transfer of integral number of electrons)

Question 4: Charge on a body is integral multiple of ±e . It is given by law of

1. Conservation of charge
2. Conservation of mass
3. Conservation of energy
4. Quantisation of charge

Question 5: In the process of charging, the mass of the negatively charged body

1. Increases
2. Decreases
3. Remains constant
4. None of the above

Question 6: Charge Q is kept in a sphere of 5 cm of first and then it is kept in a cube of side 5 cm, the outgoing flux will be

1. More in case of sphere
2. More in case of cube
3. Same in both cases
4. Information incomplete

Answer: C (Same in both cases)

Question 7: If Electric field is along X direction and the work done in moving a charge of 0.2 C through a distance of 2 m along a line making an angle of 60 º with X axis is 4 J, then what is the value of electric field?

1. √3 NC-1
2. 4 NC-1
3. 5 NC-1
4. 20 NC-1

Answer: D ( 20 NC-1  )

Question 8: Which of the following statement is true about electrical forces ?

1. Electrical forces are produced by electrical charges
2. Like charges attract and like charges repel
3. Electric Forces are weaker than gravitational forces
4. Negative charges can combined to produce a third type of charge

Answer: A (Electrical forces are produced by electrical charges )

Question 9: Which of the following statement is not a similarity between electrostatic and gravitational forces?

1. Both forces obey inverse square law
2. Both forces operate over very large distances
3. Both forces are conservative in nature.
4. Both forces are attractive in nature always

Answer: D ( Both forces are attractive in nature always )

Question 10: The constant k in Coulomb’s law depends on

1. Nature of medium
2. System of units
3. Intensity of charge
4. Both (A) and (B)

Answer: A ( Nature of medium )

Question 11: If the charge on an object is doubled then electric field becomes

1. Half
2. Double
3. Unchanged
4. Thrice

Question 12: Which of the following statements is not true about electric field lines?

1.  Electric field lines start from positive charge and end at negative charge.
2. Two electric field lines can never cross each other
3. Electrostatic field lines do not form any closed loop
4. Electric field lines cannot be taken as continuous curve

Answer: D ( Electric field lines cannot be taken as continuous curve )

Question 13: Two spherical conductors B and C having equal radii and carrying equal charges in them repel each other with a force F when kept apart at some distance. A third spherical conductor A having same radius as that of B but uncharged, is brought in contact with B, then brought in contact with C and finally removed away from both. The new force of repulsion between B and C is

1. F / 4
2. 3 F / 4
3. F / 8
4. 3 F / 8

Answer: D (3 F / 8)

Question 14: Which of the following statements about dipole moment is not true?

1. The dimensions of dipole moment is [LTA]
2. The unit of dipole moment is C m.
3. Dipole moment is vector quantity and directed from negative to positive charge
4. Dipole moment is a scalar quantity and has magnitude charge equal to the potential of separation between charge

Answer: D ( Dipole moment is a scalar quantity and has magnitude charge equal to the potential of separation between charge )

Question 15: Consider a region inside which, there are various types of charges but the total charge is zero. At points outside the region

1. The electric field is necessarily zero
2. The electric field is due to the dipole moment of the charge distribution only
3. The dominant electric field is inversely proportional to r3, for large r (distance from origin).
4. The work done to move a charged particle along a closed path, away from the region will not be zero

Answer: C (The dominant electric field is inversely proportional to r 3, for large r (distance from origin)

Question 16: Which of the following statements is not true about Gauss law?

1. Gauss’s law is true for any closed surface
2. The term q on the right side of Gauss law includes the sum of all charges enclosed by the surface
3. Gauss law is not much useful in calculating electrostatic field when the system has some symmetry
4. Gauss law is based on the inverse square dependence on distance contained in the coulomb’s law

Answer: C ( Gauss law is not much useful in calculating electrostatic field when the system has some symmetry )

Question 17: A sphere encloses an electric dipole within it. The total flux across the sphere is

1. Zero
2. Half that due to a single charge
3. Double that due to a single charge
4. Dependent on the position of dipole

Question 18: A charge q is placed at corner of the cube then the total flux through the faces of the cube with the side of length a will be

1. q / 8 ε0
2. q / 4 ε0
3. q / 2 ε0
4. q / ε0

Answer: A (q / 8 ε0

Question 19: An object is charged when it has a charge imbalance, which means the

1. Object contains no protons
2. Object contains no electrons
3. Object contains equal number of electrons and protons
4. Object contains unequal number of electrons

Answer: D ( Object contains unequal number of electrons )

Question 20: A conducting sphere is negatively charged. Which of the following statements is true?

1. In the entire volume; charge is uniformly distributed
2. The charge is located at the center of the sphere
3. The charge is located at the bottom of the sphere because of gravity
4.  The charge is uniformly distributed on the surface of the sphere

Answer: D ( The charge is uniformly distributed on the surface of the sphere )

Question 21: The number of electrons present in -1 C of charge is

1. 6 x 1018
2. 1.6 x 1019
3. 6 x 1019
4. 1.6 x 1018

Question 22: A cup contains 250 g of water. Find the total positive charges present in the cup of water.

1. 1.34 x 1019
2. 1.34 x 107 C
3. 2.43 x 1019 C
4. 2.43 x 107 C

Answer: B ( 1.34 x 107 C )

Question 23: The electric field required to keep a water drop of mass m just to remain suspended, when charged with one electron of charge e (take g as acceleration due to gravity) is:

1. mg
2. mg / e
3. emg
4. em / g

Question 24: An electric dipole is placed at angle of 30º with an electric field of intensity 2 x 105 NC-1 . It experiences a torque equal to 4 N m . If the dipole length is 2 cm then charge on dipole is

1. 8 m C
2. 4 m C
3. 6 m C
4. 2 m C

Question 25: How does electric flux due to a point charge enclosed by a spherical Gaussian surface get affected when its radius is increased?

1. Remain unaffected
2. Increases
3. Decreases
4. Information incomplete

Question 26: Given a uniform electric field E = 5 x 103 i NC-1, find the flux of this field through a square of 10 cm whose plane is parallel to YZ plane?

1. 35 N m2 C-1
2. 45 N m2 C-1
3. 50 N m2 C-1
4. None of these

Answer: C ( 50 N m2 C-1 )

Question 27: Two point charges having equal charges are separated by 1 m distance experience a force of 8 N. What will be the force experienced by them if they are held in water at same distance? (K water = 80)

1. 80 N
2. 1 / 10 N
3. 10 N
4. 8 N

Answer: B ( 1/ 10 N )

Question 28: Two infinite parallel sheets, separated by a distance d have equal and opposite uniform charge densities σ. Electric field at a point between the sheets is

1. σ / 2 εo
2. σ / εo
3. Zero
4. Depends upon the location of the point

Question 29: A closed surface in vacuum encloses charges -q and + 3 q. Another charge -2 q lies outside the surface. Total flux over the surface is

1. Zero
2. 2 q / εo
3. -3 q / εo
4. 4 q / εo

Answer: B (2 q / εo )

Question 30: When an electric dipole is held at an angle in a uniform electric field, the net force F and torque on the dipole are

1. F = 0 , τ = 0
2. F ≠ 0, τ ≠ 0
3. F = 0 , τ ≠ 0
4. F ≠ 0, τ = 0

Answer: C ( F = 0 , τ ≠ 0 )

Question 31: A hemisphere is uniformly charged positively. The electric field at a point on a diameter away from the centre is directed

1. Perpendicular to the diameter
2. Parallel to the diameter
3. At an angle tilted towards the diameter
4. At an angle tilted away from the diameter

Answer: A ( Perpendicular to the diameter )

Question 32: A cylindrical conductor is place near another positively charged conductor .The net charge acquired by the cylindrical conductor will be

1. Positive only
2. Negative only
3. Zero
4. Either positive or negative

Question 33: An electric dipole placed in a non uniform electric field experiences

1. Both a net torque and a net force
2. Only a force but no net torque
3. Only a torque but no net force
4. No torque and no net force

Answer: A (Both a net torque and a net force)

Question 34: An electric dipole is placed in a uniform electric field with the dipole axis making an angle with the direction of electric field. The orientation of the dipole for the stable equilibrium is

1. π / 6
2. π / 3
3. 0
4. π / 2

Question 35: What is nature of Gaussian surface involved in Gauss’ law of electrostatics?

1. Scalar
2. Electrical
3. Magnetic
4. Vector

Question 36: A charged particle is free to move in an electric field. It will travel

1. Always along a line of force
2. Along a line of force, if its initial velocity is zero
3. Along a line of force, if it has same initial velocity in the direction of an active angle with the line of force
4. None of the above

Answer: B ( Along a line of force, if its initial velocity is zero )

Question 37: Two concentric spherical shells of radii R and 2 R are given charges Q1 and Q2 respectively. The surface charge densities of the outer surfaces are equal. Determine the ration Q1 : Q2.

1. 1 : 2
2. 1 : 1
3. 1 : 4
4. None of these

Question 38: An electric dipole of dipole moment P is placed in a uniform external electric field . Then, the

1. Torque experienced by the dipole is E × p
2. Torque is zero if p is perpendicular to E
3. Torque is maximum if p is perpendicular to E
4. Potential energy is maximum if p is parallel to E

Answer: C ( Torque is maximum if p is perpendicular to E )

#### MCQ of Electrostatic Potential and Capacitance

Question 1: What is the potential at a point due to charge of 5 x 10-7 C located 10 cm away?

1. 3.5 x 105
2. 3.5 x 104
3. 4.5 x 104 V
4. 4.5 x 105 V

Answer: C (4.5 x 104 V )

Question 2: Consider a uniform electric field in the z direction. The potential is a constant

1. For any x for a given z
2. For any y for a given z
3. On the x-y plane for a given z
4. All of these

Question 3: Which of the following statements is true about the relation between electric field and potential?

1. Electric field is in the direction in which the potential decreases
2. Magnitude of electric field  is given by the change in the magnitude of potential per unit displacement normal to the equipotential surface at that point
3. In the region of strong electric field equal potential surfaces are far apart
4. Both the statements A and B are correct

Answer: D (Both the statements A and B are correct)

Question 4: A charge Q is placed at the origin. The electric potential due to the charge at a given point in space is V. The work done by an external force in bringing another charge q from infinity upto the point is

1. V / q
2. Vq
3. V + q

Question 5: Which is not true for equipotential surface for uniform electric field?

1. Equipotential surface is flat
2. Two equipotential surface cross each other
3. Electric lines are perpendicular to equipotential surface
4. Work done is zero

Answer: B ( Two equipotential surface cross each other )

Question 6: A hollow metallic sphere of radius 10 cm is charged such that the potential on its surface becomes 80 V. The potential at the centre of the sphere is

1. 80 V
2. 800 V
3. 8 V
4. Zero

Question 7: A parallel plate air capacitor is charged to a potential difference of V volts. After disconnecting the charging battery the distance between the plates of the capacitor is increased using an insulating handle. As a result the potential difference between the plates

1. Increases
2. Decreases
3. Does not change
4. Becomes zero

Question 8: A parallel plate capacitor is charged and then isolated. The effect of increasing the plate separation on charge, potential, capacitance respectively are

1. Constant, decreases, decreases
2. Increases, decreases, decreases
3. Constant, decreases, increases
4. Constant, increases, decreases

Answer : D (Constant, increases, decreases)

Question 9: When two capacitors charged to different potentials are connected by connecting wire, what is not true?

1. Charge lost by one is equal to charge gained by the other
2. Potential lost by one is equal to potential gained by the other
3. Some energy is lost
4. Both the capacitors acquire a common potential

Answer : B ( Potential lost by one is equal to potential gained by the other )

Question 10: Charge on a capacitor is doubled. Its capacity becomes k times , where

1. k = 2
2. k = 1
3. k = 1 / 2
4. k = 4

Answer : B (k = 1)

Question 11: Work done in moving a test charge on an equipotential surface is

1. Negative
2. Zero
3. Positive
4. Positive infinite

Question 12: Equipotential surfaces associated with an electric field which is increasing in magnitude along x direction are:

1. Planes parallel to yz plane
2. Planes parallel to xy plane
3. Planes parallel to xz plane
4. Coaxial cylinders of increasing radii around x axis

Answer : A (Planes parallel to yz plane)

Question 13: If a conductor has potential V ≠ 0 and there are no charge anywhere else outside

1. There must be charges on the surface or inside itself
2. There cannot be any charge in the body of conductor
3. There must be charges only on surface
4. Both A and B are correct

Answer : D (Both A and B are correct)

Question 14: Three capacitors each of capacity 4µF are to be connected in such a way that the effective capacitance is 6µF. This can be done by

1. Connecting them in series
2. Connecting them in parallel
3. Connecting two in series and one in parallel
4. Connecting two in parallel and one in series

Answer : C ( Connecting two in series and one in parallel )

Question 15: If the distance between the plates of capacitor is increased, then capacitance:

1. Increases
2. Decreases
3. Remains the same
4. First increases then decreases

Question 16: What is the capacitance of arrangement of 4 plates of area A at distance d in air? 1. 3 A εo / d
2.  A εo / d
3. 4  A εo / d
4. None of these

Answer : A (3 A εo / d )

Question 17: Find the potential difference between points A and B of arrangement shown 1. 6 V
2. 24 V
3. 8 V
4. -8 V

Question 18: A parallel plate capacitor with air between the plates
has a capacitance of 8 pF. What will be the capacitance if the distance between the plates is reduced by half, and the space between them is filled with a substance of dielectric constant 6 ?

1. 8 pF
2. 96 pF
3. 48 pF
4. 192 pF

Question 19: A combination of four identical capacitors is shown. If resultant capacitance of combination between the points P and Q is 1µF, calculate capacitance of each capacitor. 1. 14 µF
2. 40 µF
3. 4 µF
4. Information incomplete

Question 20: Equipotential surfaces

1. Are closer in regions of larger electric fields compared to regions of lower electric field
2. Will be more crowded near sharp edges of a conductor
3. Will always be equally spaced
4. Both A and B are correct

Answer: D (Both A and B are correct)

Question 21: A hexagon of side 8 cm has a charge 4µC at each of its vertices. The potential at the centre of the hexagon is

1. 2.7 x 106 V
2. 7.2 x 1011 V
3. 2.5 x 1012 V
4. 3.4 x 104 V

Answer: A ( 2.7 x 106 V )

Question 22: An electric dipole of length 20 cm having ± 3 x 10-3 C charge placed at 60º with respect to a uniform electric field experiences  a torque of 6 N m. The potential energy of the dipole is

1. –2√3 J
2. 5√3 J
3. –3√2 J
4. 3√5 J

Answer: A ( –2√3 J )

Question 23: A capacitor of capacitance C has charge Q and stored energy is W. If the charge is increased to 2 Q, the stored energy will be

1. W / 4
2. W / 2
3. 2W
4. 4W

Question 24: In a regular polygon of n sides, each corner is at a distance r from the corner. Identical charges are placed at (n-1) corners. At the centre , the magnitude of electric field intensity is E and the potential is V. The ration V/E is

1. rn
2. r (n-1)
3. (n-1 )/ r
4. r(n-1) / n

Question 25: When air is replaced by a dielectric constant K, the maximum force of attraction between two charges separated by a distance

1. Increases by K times
2. Remains Unchanged
3. Decreases by K times
4. Increases by 2K times

Answer: C (Decreases by K times)

Question 26: The voltage of the charging source constant then what would be the percentage change in the energy stored in a parallel plate capacitor if the separation between the plates were to be decreased by 10%?

1. 11.11%
2. 10%
3. 1.11%
4. None of these

Question 27: Two charged spherical conductors of radii R1 and R2 when connected by a conducting wire attain charges q1 and q2 respectively. The proportion of their surface charge densities in terms of their radii is

1. R1 2 : R2 2
2. R2 3 : R1 3
3. R2 : R1
4. None of these

Answer: C (R2 : R1 )

Question 28: What will be the electric potential if A, B and C are the three points in a uniform electric field? 1. Maximum at A
2. Maximum at B
3. Maximum at C
4. Same at all the three points A, B and C

Question 29: A parallel plate capacitor is maintained at a certain potential difference. When a 3 mm thick slab is introduced amid the plates, in order to maintain the same potential difference, the distance between the plates is enlarged by 2.4 mm. Find the dielectric constant of the slab.

1. 4
2. 3
3. 5
4. Information incomplete

Question 30: Electric field is always

1. Parallel to equipotential surface
2. Perpendicular to equipotential surface
3. It can be perpendicular and parallel as well
4. It does not depend on distribution of charge

Answer: B (Perpendicular to equipotential surface)

Question 31: If n number of equal capacitors each of capacitance C are connected in series, then equivalent capacitance will be

1. n x C
2. C/n
3. n + C
4. n2 C

Answer: B ( C/ N )

Question 32: A dipole is placed parallel to electric field. If W is the work done in rotating the dipole from 0º to 60º, then work done in rotating it from 0º to 180º is

1. 2 W
2. 3 W
3. 4 W
4. W / 2

Question 33: Electrical capacity of earth is

1. 1 F
2. 1 µF
3. 711 µF
4. 9 x 109 µF

Question 34: Three capacitors of capacitance 1 µF, 2µF and 3µF are connected in series and a potential difference of 11 V is applied across the combination, then the potential difference across the plates of 1µF capacitor is

1. 2 V
2. 4 V
3. 1 V
4. 6 V

Question 35: A condenser is charged to double its initial potential. The energy stored in the condenser becomes x times, where x =

1. 2
2. 4
3. 1
4. 1/2

Question 36: Which of the following is false for a perfect conductor?

1. The surface of conductor is an equipotential surface
2. The electric field just outside the surface of conductor is perpendicular to the surface
3. The charge carried by a metallic sphere is always uniformly distributed over its surface
4. None of these

Question 37: What is the Dielectric constant for a metal?

1. Zero
2. Infinite
3. 1
4. 10

#### MCQ of Current Electricity

Question 1: The electrical resistance of a conductor depends upon

1. Size of conductor
2. Size of conductor
3. Geometry of conductor
4. All of these

Answer  :  D ( All of these )

Question 2:Electromotive force is able to maintain  a constant

1. Current
2. Resistance
3. Power
4. Potential difference

Answer  :  D ( Potential Difference )

Question 3:When a metal conductor connected to left gap of a meter bridge is heated, the balancing point

1. Shifts towards right
2.  Shifts towards left
3. Remains unchanged
4. Remains at zero

Answer  :  A ( Shifts towards right )

Question 4: In a wheat stone bridge if the battery and galvanometer are interchanged then what will be affect on the galvanometer deflection

1. Change in previous direction
2. Not change
3. Change in opposite direction.
4. None of these.

Answer  : B ( not change )

Question 5:In series combination of n cells, we obtain

1. More voltage
2. More current
3. Less voltage
4. Less current

Answer : B ( More voltage )

Question 6:Which statement is correct about the validity of Kirchhoff’s loop rule

1. It lies on conservation of charge.
2. Departing currents add up and are equal to incoming currents at a junction.
3. Flexing or reorienting the wire does not change the validity of Kirchhoff’s junction rule.
4. All of these

Answer : D ( All of these )

Question 7:Choose the correct dimensional formula of resistance

1. [MLT-3A-2]
2. [MLT-1A-3]
3. [ML1 T-3A-2]
4. [MLT-3A-1]

Answer  : A ( [MLT-3A-2] )

Question 8:A negative charge is moving via junction, then

1. Momentum will be conserved.
2. Momentum will not be conserved.
3. At some places momentum will be conserved and at some other places momentum will not be conserved , it depends on place where the charge is placed
4. None of these.

Answer  D : ( None of these )

Question 9: Match the column as follows

 Column I Column 2 A Ohm’s Law is valid to- P -metals B Ohm’s law is not valid to- Q -greater resistivity C alloys have- R -diodes and semiconductors
1. A-R , B-R , C-R
2. A-P , B-R , C-Q
3. A-R , B-P , C-Q
4. A-Q , B-R , C-P

Answer  : B ( A-P , B-R , C-Q )

Question 10:In a potentiometer furnished with 20 wires, the balance point is acquired on the 17th wire. To shift the balance point to 19th wire, we should do as follows

1. Should decrease resistance of the main circuit.
2. Should increase resistance of the main circuit.
3. Should decrease resistance in series with the cell whose EMF is to be find out.
4. Should increase resistance in series with the cell whose EMF is to be find out.

Answer  : D ( Increase resistance in series with the cell whose EMF is to be find out. )

Question 11:(A). Current flows in a conductor only when there is an external electric field applied to the conductor.

(B).The drift velocity of electrons is directly proportional to the electric field.

1. Only A is correct
2. Only B is correct
3. Both A & B are correct
4. Both A and b are false

Answer : C ( Both A & B are correct )

Question 12:What is the value of unknown resistance R, if galvanometer shows null deflection in the given meter bridge set up? 1. 97.50 Ω
2. 105 Ω
3. 150 Ω
4. 110 Ω

Answer  : A ( 97.50 Ω )

Question 13:If you have a positive charge ,what conclusion can be drawn about current density?

1. Direction of current and current density is opposite
2. Direction of current and current density is same
3. Current density and current are independent
4. direction can not be determined

Answer : B ( Direction of current and current density is same )

Question 14:Specify the value of resistance if carbon code is

Green – Brown – Yellow – Gold

1. 50 X 104 ± 4%
2. 51 X 104 ± 5%
3. 47 X 103 ± 2%
4. 32 X 105 ± 5%

Answer  : B ( 50 X 104 ± 5% )

Ques 15:Which is correct expression for microscopic form of ohm’s law

1. E=J.ρ
2. J=E.σ
3. E=ρ.I/A
4. All of the above

Answer : D ( All of the above )

Question 16: Specify the relation between EMF of a cell and external resistance

1. EMF of a cell depends directly on external resistance
2. EMF of a cell depends directly on external resistance
3. EMF of a cell is independent of external resistance
4. EMF of a cell first increases and then decreases with external resistance

Answer  : C ( EMF of a cell is independent of external resistance )

Question 17:When the cells are connected in mixed grouping

1. High EMF is obtained
2. High current is obtained
3. High power is obtained
4. None of these

Answer  : C ( High power is obtained )

Question 18: In series combination of n cells , having an EMF ‘E’ and internal resistance ‘r’ . If 3 cells are wrongly connected, what will be the total EMF and internal resistance

1. EMF= n*E;  r=6Ω
2. EMF= nE-6E;  r=independent
3. EMF=independent ;  r=1Ω
4. EMF= n/6E;  r=independent

Question 19:Which of the following is not an application of wheat stone bridge

1. To find unknown resistance
2. To find specific resistance
3. To compare EMF of two cells
4. To verify resistance whether in series or parallel combination

Answer : C ( To compare EMF of two cells )

Question 20:Wheat stone bridge can be used to determine ________value of resistors?

1. High value only
2. Low value only
3. Moderate Value only
4. All of the above

Answer : C ( Moderate value only )

Question 21: Which of the following is an application of potentiometer

1. To measure potential drop of a certain section
2. To compare the EMF of two cells
3. To find internal resistance of a cell
4. All of the above

Answer :  D( All of these )

Question 22: EMF of a cell is less than the terminal potential difference when

1. Charging condition
2. Always
3. Discharging condition
4. Never

Answer : A ( Charging condition )

Question 23:In a combination on ‘n ‘cells , if the polarity of ‘m’ cells is reversed,

1. E eq=n E
2. E eq=(n-2 m)E
3. E eq=(n-2 m)/E
4. E eq=(n+2 m)/E

Answer  : B ( E eq=(n-2 m)E )

Question 24: Ramesh has 12 old cells . He needs maximum output out of these, in which of the following combinations ,he must connect the respective cells

1. Cells should be connected in series combination
2. Cells should be connected in parallel combination
3. Cells should be connected in mixed grouping
4. Nothing can be done

Answer : B ( Cells should be connected in parallel combination )

Question 25:Which of the following is correct about temperature coefficient of metals and alloys

1. (Temperature coefficient of metals)>(temperature coefficient of alloys)
2. (Temperature coefficient of alloys)>(temperature coefficient of alloys)
3. Temperature coefficient of metals is nearly equal to temperature coefficient of alloys
4. (Temperature coefficient of alloys)<=(temperature coefficient of alloys)

Answer : A ( (Temperature coefficient of metals)>(temperature coefficient of alloys) )

Question 26: Which of the following must be constant for the validity of Ohm’s Law

1. Temperature
2. Pressure
3. Mechanical strain
4. All of these

Answer  : D ( All of these )

Question 27:Why standard resistors are made up of alloys (specifically manganin and constantan)

1. These alloys have high temperature coefficients
2. These alloys have low temperature coefficients
3. These alloys have high resistivity
4. Both B & C

Answer  : D ( Both B and C )

Question 28:How does relaxation time and temperature related to each other

1. Relaxation time varies inversely with temperature
2. Relaxation time varies directly with temperature
3. Relaxation time is independent of temperature
4. Relaxation time first increases and then decreases with temperature

Answer  : A( Relaxation time varies inversely with temperature )

Question 29:What is the direction of  electronic current?

1. Positive to negative
2. Negative to positive
3. Undefined
4. Parallel to electric field

Answer : B ( Negative to positive )

Question 30:How the values of magnitude and direction varies with time for steady direct current?

1. Magnitude changes with time ;direction remains unchanged
2. Magnitude remains unchanged ; direction changes with time
3. Magnitude changes with time ; direction also changes with time
4. Magnitude remains unchanged ; direction also remains unchanged

Answer : D ( Magnitude remains unchanged ; direction also remains unchanged )

Question 31:A boy has two spare light bulbs in his drawer. One is marked 240 V and 100 W and the other is marked 240 V and 60 W. He tries to decide which of the following assertions are correct?

1. The 60 W light bulb has more resistance and therefore burns less brightly.
2. The 60 W light bulb has less resistance and therefore burns less brightly.
3. The 100 W bulb has more resistance and therefore burns more brightly.
4. The 100 W bulb has less resistance and therefore burns less brightly.

Answer : A ( The 60 W light bulb has more resistance and therefore burns less brightly. )

Question 32: The resistance of the wire in platinum resistance thermometer at ice point is 5Ω and at steam point is 5.25Ω .When the thermometer is inserted in an unknown hot bath its resistance is found yo be 5.5Ω.The temperature of hot bath is

1. 100°C
2. 200°C
3. 300°C
4. 350 °C

Answer : B ( 200°C )

Question 33: A battery , an open circuit and a resistor are connected in series . Consider the following 3 statements concerning the circuit . A voltmeter will read zero if it is connected across points

(i)P and T

(ii)P and Q

(iii)Q and T

Which one of the above is/are true?

1. Only(i)
2. only (iii)
3. Only(i and iii)
4. (i),(ii) and 9(iii)

Answer  : C ( Only(i and iii) )

Question 34:The resistivity of alloy manganin is

1. Nearly independent of temperature
2. Increase rapidly with increase in temperature
3. Decrease rapidly with increase in temperature
4. Increase rapidly with decrease in temperature

Answer A : ( Nearly independent of temperature )

Question 35: The correct combination of three resistance 1Ω,2Ω and 3Ω to equivalent resistance 11/5Ω is

1. All three are combined in parallel
2. All three are combined in series
3. 1Ω and 2Ω in parallel and 3Ω in series to both
4. 2Ω and 3Ω are combined in parallel and 1 Ω is in series to both

Answer : D ( 2Ω and 3Ω are combined in parallel and 1 Ω is in series to both )

#### MCQ of Moving Charges and Magnetism

Question 1 : A negatively charged particle is placed across a current carrying wire . Is any force experienced by the charged particle? 1. Due to the effect of electric field , the force will be experienced by the charged particle towards right .
2. Due to the effect of electric field , the force will be experienced by the charged particle towards left .
3. A Torque will be applied due to the effect of magnetic field .
4. No force will be experienced by the charged particle .

Answer : C ( A torque will be applied due to the effect of magnetic field . )

Question : 2 Give the unit of magnetic field .

1. Tesla
2. W b m-2
3. N C-1 -1 s
4. All of the above

Answer : D ( All of the above )

Question 3 : Select the CGS unit of magnetic field .

1. Gauss
2. Tesla
3. Weber
4. Maxwell

Answer A : ( Gauss )

Question 4 : which is the correct expression for the magnetic field about infinite length conductor

A. ( μ/4π ). ( I/a )
B. ( μ/4π ). 2 ( I/a )
C. ( μ/4π ). ( I/a ). sin ( 90° )
D. ( μ/4π ). ( I/2a )

Answer : B ( ( μo/4π ). 2 ( I/a ) )

Question 5 : Consider two concentric loops , inner and outer loop having radii ‘R1’ and ‘R2’ respectively . Inner loop having current ‘I1’ ( clockwise ) and outer loop having current ‘I2’ ( anti – clockwise ) generates magnetic field as ‘B1’ and ‘B2’ respectively .
If I1 > I2 then B net =

A. B1 – B2
B. B1 + B2
C. B2 – B1
D. None of these

Answer : A ( B1 – B2 )

Question 6 : Ampere’s Circuital law is valid for

A. Direct current

C. Both A and B
D. Electronic Current

Answer : A ( Direct Current )

Question 7 : Magnetic field around a cylindrical wire is maximum at

A. Axis of cylinder
B. Outside the cylinder
C. Inside the cylinder
D. At surface of the cylinder

Answer : D ( At surface of the cylinder )

Question 8 : When magnetic field of certain magnitude is applied to an electron at rest , then

A. Electron will move in the same direction as that of electric field
B. Electron will remain stationary
C. Electron will move perpendicular to the direction of electric field
D. Electron will move opposite to the direction of electric field.

Answer : B ( Electron remains stationary )

Question 9 : A negatively charged particle is moving in a elliptical path with a velocity V in uniform magnetic field B , If the charged particle is accelerated to double its velocity and strength of magnetic field is reduced to half , then what how the radius of loop will be affected

A. 8 times
B. 4 times
C. 2  times
D. 16 times

Answer : B ( 4 times )

Question 10 : A charged particle is moving in a region with a constant velocity . Which of the following statement is incorrect

A. E = 0 , B ≠ 0 ( Electric field is zero but magnetic field is non –  zero )
B. E ≠ 0 , B ≠ 0 ( Both electric field and magnetic field are non – zero )
C. E ≠ 0 , B = 0 ( Electric field is non – zero but magnetic field is zero )
D. E = 0 , B = 0 ( Both Electric field and magnetic field is zero )

Answer : C ( E ≠ 0 , B = 0 ( ( Electric field is non – zero but magnetic field is zero ) )

Question 11 : The frequency of cyclotron is given by

A. q b / 2πm
B. m B / 2πq
C. 2πm / q b
D. 2πm / q b

Answer : A ( q B / 2πm )

Question 12 : Which of the following statement in relation to magnetic force is accurate ?

A. Magnetic forces always stick to Newton’s third law
B. Magnetic forces don’t stick to Newton’s third law
C. Only for high current , magnetic forces follow Newton’s third law
D. Inside low magnetic field , magnetic forces stick to Newton’s third law

Answer : B ( Magnetic forces don’t stick to Newton’s third law )

Question 13 : A circular loop of radius 10 cm having 100 turns is carrying a current of 3.2 A .The loop is placed in vertical plane and is free to rotate around a horizontal and the vertical plane coincides with diameter of the loop. A uniform magnetic field of 5 T remains such that initially the axis of the coil is in direction of the field . Under the effect of magnetic field , the coil rotates through an angle of 60° . The magnitude of torque in the final position is

A. 25 N m
B. 25 √3 N m
C. 40 N m
D. 40 √3 N m

Answer : B ( 25 √3 N m )

Question 14 : Consider two wires , carrying current flowing in parallel and anti – parallel directions , then

A. Parallel currents repel each other anti parallel currents attract each other .
B. Parallel currents attract each other and antiparallel currents repel each other
C. Both currents attract each other
D. Both currents repel each other

Answer : B ( Parallel currents attract each other and antiparallel currents repel each other )

Question 15 : Which of the following is incorrect about cyclotron ?

A. It is a machine to whisk charged particles or ions to high energy.
B. Cyclotron utilizes both electric and magnetic field in combination to increment the energy of              charged particles .
C. The cyclotron sticks to the logic that the time for one revolution of an ion is independent of its            speed or radius of its orbit .
D. The charged particles can move in cyclotron on an arbitrary path .

Answer : D ( The charged particles can move in cyclotron on an arbitrary path. )

Question 16 : A coil having 90 turns of radius 15 cm having a magnetic field of 4× 10-4 Tesla . The amount of current flowing through it is

A. 1.06 A
B. 2.44 A
C. 3.44 A
D. 4.44 A

Answer : A ( 1.06 A )

Question 17: A moving coil galvanometer can be converted into an ammeter by doing the following step

A. By introducing a resistor of large value in series .
B. By introducing a shunt in parallel .
C. By introducing a resistor of small value in series .
D. By introducing a resistor of large value in parallel .

Answer : B ( By introducing a shunt in parallel )

Question 18 : An electron is moving with a velocity of 3.2 × 107 m s-1 in a magnetic field of 5 × 10-4 Tesla which is perpendicular to it . What will be the frequency of this electron ?

A. 1.4 × 10 5 Hz
B. 1.4 × 10 7 Hz
C. 1.4 × 10 6 Hz
D. 1.4 × 10 9 Hz

Answer : B ( 1.4 × 10 7 Hz )

Question 19 : Due to the effect of current in a circular loop having two turns  a magnetic induction of 0.2 T is produced at its center . The loop is the reoriented into circular loop of four turns . If same amount of current flows in the cold then the magnetic induction at the center of the loop now is

A. 0.2 T
B. 0.4 T
C. 0.6 T
D. 0.8 T

Answer : D ( 0.8 T )

Question 20 : If an electron is moving with velocity V and produces a magnetic field , then
A. The direction of magnetic field will be same as direction of velocity .
B. The direction of magnetic field will be opposite to the direction of velocity .
C. The direction of magnetic field will be perpendicular the direction of velocity .
D. The direction of magnetic field does not depend upon the direction of velocity .

Answer : C ( The direction of magnetic field will be perpendicular the direction of velocity .)

Question 21: Pick out the condition in which no force is experienced by the charged particle placed in magnetic field

A. If a charged particle is at rest.
B. If a charged particle is placed parallel to the magnetic field.
C. If a charged particle is placed antiparallel to the magnetic field.
D. All of these

Answer : D ( All of these )

Question 22 : Is it charged particle is moving in a cyclotron then how will the radius of the path be affected if the frequency of the radio frequency field is doubled ?

A. The radius of path will also become half of the initial radius.
B. The radius of part will be increased four times.
C. The radius of path will be increased 8 times.
D. The radius of path will remain unchanged.

Answer : D ( The radius of path will remain unchanged )

Question 23 : A positively charged particle is moving in a cyclotron having an external magnetic field of 1 T . If its oscillating frequency is 11 MHz and radius is 55 cm , then its kinetic energy in MeV is

A. 13.36
B. 12.52
C. 14.89
D. 14.49

Answer : D ( 14.49 )

Question 24 : A circular loop of 10 cm radius having 20 turns , is placed in a uniform magnetic field of 0.10 T . Given that the magnetic field is normal to the plane of coil . If the loop has cross – sectional area of 10-5 m2 , current flowing in the loop is 5 A and coil is made up of Cu having free electron density about an order of 1029 m3 . Find the net magnetic force on the loop .

A. 2.5 × 10-25
B. 5 × 10-25
C. 4 × 10-25
D. 3 × 10-25

Answer : B ( 5 × 10-25 )

Question 25 : When a magnetic compass needle is placed near a straight current carrying wire , then
(i) The straight current carrying wire will lead to a noticeable deflection in the compass needle
The needle will be aligned tangential to an imaginary circle with the straight current carrying wire

A. Both ( i ) and ( ii ) are correct
B. Only ( ii ) is correct
C. Only ( i ) is correct
D. Neither ( i ) nor ( ii ) is correct .

Answer : A ( Both ( i ) and ( ii ) are correct )

Question 26 : Which of the following is incorrect statement about the Lorentz Force ?

A. F = q [ E ( r ) + B ( r ) ] will be the force acting on a moving charge particle in the presence of                electric field E ( r ) and magnetic field B ( r ) .
B. This force depends on the nature of charged particle as the magnetic field due to a negative                  charge is opposite to that of A positively charged .
C. If the velocity and the magnetic field at parallel and anti – parallel the force due to magnetic               field then the force becomes zero .
D. The magnetic force will be maximum for a static charge .

Answer : D ( The magnetic force will be maximum for a static charge . )

Question 27 : In an inertial frame of reference if the magnetic force applied on a moving charged particle is F then what will be its value in another inertial frame of reference

A. It does not depends on the inertial frame of reference therefore the force will remains same.
B. The force will be changed due to the change in the amount of charge
C. The force will be changed due to the change in velocity of charged particle .
D. The force will be changed due to the change in field direction.

Answer : C ( The force will be changed due to the change in velocity of charged particle)

Question 28 : When a Proton enters a uniform magnetic field with uniform velocity then what will be its trajectory

A. Helical
B. Circular
C. Straight line
D. Any one of A , B and C

Answer : D ( Any one of A , B and C )

Question 29 : A circular loop carrying current I having radius R is placed in a uniform magnetic field B which is perpendicular to the loop the force on the loop will be ,

A. 2π RIB
B. 2π R I2 B3
C. π R2 I B
D. Zero

Answer : D ( zero )

Question 30 : A straight current carrying wire of length 1 m having current of 5 ampere is suspended in mid – air by a uniform horizontal magnetic field , then find the magnitude of magnetic field given that the mass of straight current carrying wire is 1.2 Kg

A. 0.65 T
B. 1.53 T
C. 2.4 T
D. 3.2 T

Answer : C ( 2.4 T )

Question 31 : An electron enters cube across one of its face and cubical box is filled with uniform electric field and the magnetic field . If the velocity of electron is V E and A positron enters via opposite face with a velocity of – V . At a instant of time which of the following is not correct ?

A. The electric forces on both the particles will cause same acceleration in the electron and a                    positron
B. The magnetic forces on both a particle will cause identical acceleration in the electron and                    positron
C. Both the particles , electron and positron will gain or lose some energy at same rate .
D. The motion of center of mass will be determined by magnetic field only.

Answer : A ( The electric forces on both the particles will cause same acceleration in the electron and a positron )

Question 32 : A toroid is having 3700 turns with its inner and Outer radius as 28 cm and 29 cm respectively . If the current in the toroid is of then a then what will be the magnetic field inside the core of toroid .

A. 2.60 × 10 ^ – 2 T
B. 2.60 × 10 ^ – 3 T
C. 4.53 × 10 ^ – 2 T
D. 2.60 × 10 ^ – 3 T

Answer : A ( 2.60 × 10  – 2 T )

Question 33 : A straight current carrying wire ‘ A ‘ of length 10 m having current of 4 A is placed parallel at a distance of 3 m with a wire ‘ B ‘ of length 12 m and having a current of 6 A in opposite direction . Find the force on a 15 cm section of wire B near its center .

A. 2.4 × 10 -5 N ( attractive nature )
B. 2.4 × 10 -5 N ( repulsive nature )
C. 1.2 × 10 -5 N ( attractive nature )
D. 1.2 × 10 -5 N ( repulsive nature )

Answer : B ( 2.4 × 105 N ( repulsive nature ) )

Question 34 : A galvanometer can be transformed into a voltmeter by doing the following step : –

A. By introducing a resistance of very large value in series combination with the galvanometer .
B. By introducing a resistance of very small value in parallel combination with galvanometer .
C. By introducing a resistance of very large value in parallel combination with the galvanometer .
D. By introducing a very small value of resistor in series combination with the galvanometer .

Answer : A ( By introducing a resistance of very large value in series combination with the galvanometer . )

Question 35 : For a sodium atom what will be the value of Gyromagnetic ratio of an electron .

A. The Gyromagnetic ratio will depend upon the atomic number of the atom
B. The Gyromagnetic ratio will depend on the number of shells of the atom
C. Gyromagnetic ratio will be independent of the orbit of the atom.
D. Gyromagnetic ratio will have a positive value

Answer : C ( Gyromagnetic ratio will be independent of the orbit of the atom )

Question 36 : A galvanometer of resistance 50 Ohm provides a full scale deflection for a current of 0.0 5A . If the cross-sectional area of resistance wire is 3 x 10-2 that can be used to convert the galvanometer into an ammeter which can read a maximum value of 5 A current it , then calculate the length of the wire . Given that the specific resistance of wire is 5 x 10-7 ohm m.

A. 9 m
B. 6 m
C. 3 m
D. 1.5 m

Answer : C ( 3 m )

Question 37 : Which of the following is accurate value of the Bohr magneton ?

A. 8.99 × 10-24 A m-2
B. 9.27 × 10-24 A m-2
C. 5.66 × 10-24 A m-2
D. 9.27 × 10-28 A m-2

Answer : B ( 9.27 × 10-24 A m-2 )

Question 38 : A Galvanometer shows full scale deflection for a current of 4 mA . To convert the galvanometer into a voltmeter of range 0 to 18 V , then what will be the value of resistance required . Given that the resistance of a galvanometer coil is 15 ohm .

A. To convert the galvanometer into voltmeter a resistance of 5885 Ohm is required in series                   combination .
B. To convert the galvanometer into voltmeter a resistance of 4485 Ohm is required in series                    combination.
C. To convert the galvanometer into voltmeter a resistance of 5885 Ohm is required in parallel                combination .
D. To convert the galvanometer into voltmeter a resistance of 4485 Ohm is required in parallel                combination.

Answer : B ( To convert the galvanometer into voltmeter a resistance of 4485 Ohm is required in series combination. )

Question 39 : A Galvanometer shows full scale deflection for a current of 1 mA . To convert the galvanometer into a voltmeter of a range of 2.5 V , then what will be the value of resistance required . Given that the resistance of a galvanometer coil is 10 ohm .

A. To convert the galvanometer into voltmeter a resistance of 24.9 Ohm is required .
B. To convert the galvanometer into voltmeter a resistance of 249 Ohm is required.
C. To convert the galvanometer into voltmeter a resistance of 2490 Ohm is required .
D. To convert the galvanometer into voltmeter a resistance of 24900 Ohm is required .

Answer : C ( To convert the galvanometer into voltmeter a resistance of 2490 Ohm is required)

Question 40 : The torque acting on a current carrying loop which is please in uniform magnetic field does not depend on

A. The torque not depend on the area loop
B. The torque not depend on the value of current
C. The torque not depend on the magnetic field of the loop.
D. None of these

Answer : D ( None of these )

Question 41 : Find the kinetic energy in MeV of a proton if the radius of its dees is 60 cm and frequency of cyclotron oscillator is 12 MHz

A. Kinetic energy is 5 MeV
B. Kinetic energy is 6.5 MeV
C. Kinetic energy is 10.6 MeV
D. Kinetic energy is 12.6 MeV

Answer : C ( Kinetic energy is 10.6 MeV )

Question 42 : In a uniform magnetic field of 5t the coil has a magnetic moment of 25 a M2 if the if the coil rotates with an angle of 60 degree under the influence of magnetic field is

A. 216.5 N m
B. 108.25 N m
C. 102.5 N m
D. 258.1 N m

Answer : B ( 108.25 N m )

#### MCQ of Magnetism and Matter

Question 1 : Pick out the origin of magnetic field

1. Intrinsic spin of electrons and electric Current
2. Polarity of molecules
3. Pauli’s exclusion principle
4. Electronegativity of materials

Answer : A ( Intrinsic spin of electrons and electric Current )

Question 2 : Which of the following statements is incorrect about the magnetic field lines

1. The magnetic lines of force form continuous closed loops
2. By drawing a tangent to magnetic field lines , we can get the direction of net magnetic field
3. As the number of magnetic field lines increases , magnetic force also increases and vice versa .
4. The magnetic lines of force meet each other at certain points.

Answer : D ( The magnetic lines of force intersect each other at certain points. )

Question 3 : Which of the following is true about magnetic monopole ?

1. Monopole of magnet exists
2. Monopole of magnet does not exists .
3. Momentum is constant for magnetic monopole.
4. Momentum varies in case of magnetic monopole as the distance from the field increases.

Answer : B ( Monopole of magnet does not exists .)

Question 4 : A long solenoid having a magnetic moment ‘M’ which corresponds to bar magnet is

1. Magnetic dipole moment will be Equal for both bar magnet and solenoid
2. More magnetic moment for solenoid
3. More magnetic moment for bar magnet
4. None of these

Answer : A ( Equal for both )

Question 5 : Which of the following statements is correct about B.E and B.A?

(B.E represents equatorial magnetic field and B.A refers to axial magnetic field due to bar magnet . )

1. B.E = 2 B.A
2. B.A = 2 B.E
3. B.E = 4 B.A
4. B.A = 4 B.E

Answer : B ( B.A = 2 B.E )

Question 6 : Magnetic moment of a short bar magnet is 0.48 JT-1 . Select the magnitude and direction of magnetic field , which is produced by magnet at a distance of 10 cm from the center of magnet on its axis

1. 0.48 × 10 -4 T along north – south direction
2. 0.28 × 10 -4 T along south – north direction
3. 0.28 × 10 -4 T along north – south direction
4. 0.96 × 10 -4 T along south – north direction

Answer : D ( 0.96 × 10 -4 T along south – north direction )

Question 7 : Magnetic moment of a short bar magnet is 0.39 JT-1 . Select the magnitude and direction of magnetic field , which is produced by magnet at a distance of 20 cm from the equatorial line of the magnet

1. 0.049 G along north – south direction
2. 4.95 G along south – north direction
3. 0.0195 G along south – north direction
4. 19.5 G along north – south direction

Answer : A ( 0.049 G along north – south direction )

Question 8 : Identity the unlike pair

1. ‘Hard magnet’ is associated with ‘alnico’
2. ‘Soft magnet’ is associated with ‘ soft iron’
3. ‘ Bar magnet ‘ is associated with ‘ Equivalent solenoid ‘
4. ‘ Electromagnet is associated with ‘ loud speaker ‘

Answer : D ( ‘ Electromagnet is associated with ‘ loud speaker ‘)

Question 9 : Which material is best to be used in making galvanometer ‘s coil .

1. Cu
2. Ni
3. Fe
4. Both A and B

Answer : C ( Fe )

Question : 10 To reduce residual magnetism to zero by applying magnetizing field in opposite direction is known as :

1. Retentivity
2. Coercivity
3. Hysteresis
4. Flux

Answer : B ( Coercivity )

Question 11 : Earth behaves as a magnet , what is the direction of magnetic field geographically

1. North to south (N-S)
2. South to north (S-N)
3. East to west (E-W)
4. West to east ( W-E)

Answer : B ( South to north(S-N) )

Question 12 : Which of the following entity is not used in specifying earth’s magnetic field ?

1. Magnetic declination
2. Magnetic dip
3. Horizontal component of earth ‘s magnetic field
4. Vertical component of earth ‘ s magnetic field

Answer : D ( Vertical component of earth ‘ s magnetic field )

Question 13 : Which of the following is not a significant difference between electrostatic shielding by a conducting shell and magneto-static shielding ?

1. Electric field lines can terminate on charges and conductors have free charges
2. Magnetic field lines can terminate but conductors can not end them .
3. Magnetic field lines can never terminate on any material and ideal shielding is impossible
4. Highly permeable shells can be used to divert magnetic field lines from the interior region

Answer : B ( Magnetic field lines can terminate but conductors can not end them .)

Question 14 : The earth departs from its dipole shape at a very large distance about an order of 3 × 103 Km. The major factor responsible for this distortion is

1. Motion of ions in the ionosphere
2. Motion of ions in the atmosphere
3. Motion of ions in the lithosphere
4. Motion of ions in the mesosphere

Answer A : (Motion of ions in the ionosphere )

Question 15 : Find the angle of dip at which the horizontal component of earth is merely equal to the vertical component of the Earth’s magnetic field

1. 30°
2. 75°
3. 60°
4. 45°

Answer D : ( 45 ° )

Question 16 : Find the angle of dip at which the vertical component of earth is merely equal to √3 times the horizontal component of the Earth’s magnetic field

1. 30°
2. 75°
3. 60°
4. 45°

Answer C ( 60 ° )

Question 17 : Find the angle of dip at a place where the horizontal component of Earth’s magnetic field is 2 × 10-5 and resultant field is 4 × 10-5 .

1. 30°
2. 60°
3. 90°
4. 45°

Answer : B ( 60 ° )

Question 18 : Some of the substances are given below them maximum magnetic susceptibility ?

1. Calcium
2. Chromium
3. Oxygen
4. Tungsten

Answer : B ( Chromium )

Question 19 : If the temperature of Nickel is increased beyond the Curie temperature then what will happen , given that the liquid shows paramagnetic property at room temperature

1. Anti ferromagnetism will be observed in nickel
2. No magnetic property will be observed in nickel
3. Diamagnetism will be observed in nickel
4. Para – magnetism will be observed in nickel

Answer : D ( Para – magnetism will be observed in nickel )

Question 20 : Pick out the incorrect statement about the magnetic properties of soft iron and steel.

1. Retentivity of soft iron is greater than the retentivity of Steel.
2. Coercivity of soft iron is smaller than coercivity of steel.
3. Area of B-H loop in soft iron is less than the area of B – H loop for steel.
4. Area of B-H loop in soft iron is more than the area of B – H loop for steel.

Answer : D ( Area of B-H loop in soft iron is more than the area of B – H loop for steel.)

Question 21 : What is the value of angles of dip at poles and equator ?

1. Angle of dip at poles is 30° and at equator is 60° .
2. Angle of dip at poles is 0° and at equator is 90° .
3. Angle of dip at poles is 45° and at equator is 90° .
4. Angle of dip at poles is 90° and at equator is 0° .

Answer : D ( Angle of dip at poles is 90° and at equator is 0° )

Question 22 : Find the dipole moment on equator if the equatorial magnetic field of Earth is 0.4 G .

1. Dipole moment on equator is 1.05 × 1023 A m2 .
2. Dipole moment on equator is 2.05 × 1023 A m2 .
3. Dipole moment on equator is 1.05 × 1021 A m2 .
4. Dipole moment on equator is 2.05 × 1021 A m2 .

Answer : A ( Dipole moment on equator is 1.05 × 1023 A m2 . )

Question 23 : The strength of geomagnetic field is
Note :- ( Geomagnetic field is referred to earth’s magnetic field )

1. It remains constant everywhere .
2. It is zero everywhere .
3. It is having a very high value .
4. It vary from place to place on the earth’s surface .

Answer : D ( It vary from place to place on the earth’s surface )

Question 24 : The dipole axis and the axis of earth collectively combine to form a plane ‘S’ . If ‘P’ be the point of intersection of the geographical and the magnetic equator then but will be the angle of declination and the dip angle at point P ?

1. Angle of declination is 0° and angle of dip is 11.3°
2. Angle of declination is 11.3° and angle of dip is 0°
3. Angle of declination is 11.3° and angle of dip is 11.3°
4. Angle of declination is 0° and angle of dip is 0°

Answer : B ( Angle of declination is 11.3° and angle of dip is 0° )

Question 25 : Which of the following is correct expression for the net magnetic flux through any closed surface kept in magnetic field

1. Zero
2. μο/4π
3. 4πμo
4. 4μo/π

Answer : A ( Zero )

Question 26 : The horizontal component of Earth’s magnetic field is is 0.3 G and the vertical component of earth’s magnetic field is 0.52 G then what will be the value of earth’s magnetic field and the angle of dip

1. Earth’s magnetic field is is 0.3 G and angle of dip is 30° .
2. Earth’s magnetic field is is 0.4 G and angle of dip is 40° .
3. Earth’s magnetic field is is 0.5 G and angle of dip is 50° .
4. Earth’s magnetic field is is 0.6 G and angle of dip is 60° .

Answer : D ( Earth’s magnetic field is is 0.6 G and angle of dip is 60° )

Question 27 : Which is the foremost reason responsible for earth’s magnetic field

1. Earth’s magnetic field is due to convective currents in the earth’s core
2. Earth’s magnetic field is due to diversive currents in the earth’s core
3. Earth’s magnetic field is due to rotational motion of earth .
4. Earth magnetic field is due to translational motion of earth .

Answer : A ( Earth’s magnetic field is due to convective currents in the earth’s core )

Question 28 : Which of the following is imprecise statement about the relative magnetic permeability

1. Relative magnetic permeability of a material is dimensionless .
2. Relative magnetic permeability for vacuum medium is one .
3. Relative magnetic permeability for ferromagnetic material is always greater than 1 to large extent.
4. Relative magnetic permeability for paramagnetic material is greater than one .

Answer : D ( Relative magnetic permeability for paramagnetic material is greater than one )

Question 29 : Pick out the correct option which specifies the correct structure for a hysteresis cycle of a transformer core

1. Hysteresis cycle of transformer core is short and wide
2. Hysteresis cycle of transformer core is tall and narrow
3. Hysteresis cycle of transformer core is tall and wide
4. Hysteresis cycle of transformer core is short and narrow

Answer : B ( Hysteresis cycle of transformer core is tall and narrow )

Question 30 : Ramesh is supposed to do an experiment and in that experiment he found that the susceptibility of a given substance is much more greater than one then the substance possibly is

1. Diamagnetic
2. Paramagnetic
3. Ferromagnetic
4. Non – magnetic

Answer : C ( Ferromagnetic )

Question 31 : Let the magnetic field on the earth be carved by that of a point magnetic dipole at the center of the earth then what will be the angle of dip at a point on the geographical equator ?

1. Angle of dip will always be zero
2. Angle of dip can be positive negative or zero
3. Angle of dip is unbounded
4. Angle of dip is always negative

Answer : B ( Angle of dip can be positive negative or zero )

Question 32 : What will be the value of earth’s magnetic field if in the magnetic meridian of a certain place the horizontal component of Earth’s magnetic field is 0.25 G and angle is 60° .

1. 0.50 G
2. 0.52 G
3. 0.54 G
4. 0.56 G

Answer : A ( 0.50 G )

Question 33 : Given a compass needle which is pointing geographical north at a certain place where the horizontal component of earth’s magnetic field is 4 x 10-6 Wb m-2 experiences a torque of 1.2 x 10-3 N m if the magnetic moment of the compass needle is 60 A m2 then what will be the declination of the place

1. 20°
2. 45°
3. 60°
4. 30°

Answer : D ( 30° )

Question 34 : What will be the value of magnetic induction at a point 1 Å away from a Proton along with the axis of spin , given that the magnetic moment of the proton is 1.4 x 10– 6 A m2

1. 0.28 m T
2. 28 m T
3. 0.028 m T
4. 2.8 m T

Answer : D ( 2.8 m T )

Question 35 : A magnetic needle has moment of inertia of 7.8 x 10 – 6 kg m2 and has magnetic moment of 5.8 x 10– 2 Am2 if it completes 12 oscillations in 6 seconds then what will be the magnitude of magnetic field ?

1. The magnitude of magnetic field is 0.011 T
2. The magnitude of magnetic field is 0.021 T
3. The magnitude of magnetic field is 0.031 T
4. The magnitude of magnetic field is 0.041 T

Answer : B ( The magnitude of magnetic field is 0.021 T )

Question 36 : The work done in moving a dipole having a magnetic dipole moment of 0.5 Am2 from its most stable condition to most unstable position in a 0.0 9 T in uniform magnetic field is

1. Work done 0.07 J
2. Work done 0.08 J
3. Work done 0.09 J
4. Work done 0.1 J

Answer : C ( Work done 0.09 J )

Question 37 : A wire is placed between the two poles of of bar magnets if small amount of current it in the wire is into the plane of the paper then what will be the direction of the magnetic force on the wire

1. The direction of magnetic force will be upwards
2. The direction of magnetic field will be downwards
3. The direction of magnetic field will be towards right
4. Direction of magnetic field will be towards left

Answer : D ( Direction of magnetic field will be towards left )

Question 38 : Two identical magnetic dipoles are placed at a separation of 2 m with their axis perpendicular to each other in the air if both of the magnetic dipoles are having in magnetic dipole moment of 2 A m2 to then what will be the Magnetic field at the midpoint between the dipoles

1. 4√5 × 10-5 T
2. 2√5 × 10-5 T
3. 4√5 × 10-7 T
4. 2√5 × 10-7 T

Answer : D ( 2√5 × 10-7 T )

Question 39 : A circular loop is placed in magnetic field such that its plane is perpendicular to the external magnetic field of of magnitude 5.0 x 10– 2 . The loop is free to move about when the coil is is turned slightly and when released it oscillates about its stable equilibrium with a frequency of 2 Hz . What will be the moment of inertia of the loop about its axis of rotation , given that the circular loop has a magnetic moment of 0.355 J T

1. 1.13 × 10-1 Kg m2
2. 1.13 × 10-2 Kg m2
3. 1.13 × 10-3 Kg m2
4. 1.13 × 10-4 Kg m2

Answer : D ( 1.13 × 10-4 Kg m2 )

Question 40 : A magnetizing field produces a magnetic flux density of 8 π T in an iron rod . What will be the relative magnetic permeability of the rod if the magnitude of magnetizing field is 2×103 A m -1 .

1. 102
2. 1
3. 104
4. 103

Answer : C ( 104 )

#### MCQ of Electromagnetic Induction

Question 1: In Faraday’s experiment on electromagnetic induction, more deflection will be shown by the galvanometer, when

1. Magnet is in constant motion towards the coil
2. Magnet is in constant motion away from the coil
3. Magnet is in accelerated motion towards the coil
4. Magnet is at rest near the coil

Answer: C ( Magnet is in accelerated motion towards the coil )

Question 2: The inductance of a coil is proportional to

1. The length
2. The number of turns
3. The resistance of coil
4. The square of the number of turns

Answer: D (The square of the number of turns)

Question 3: A bar magnet is dropped between a current carrying coil. What would be its acceleration?

1. g downwards
2. Greater than g downwards
3. Less than g downwards
4. Bar will be stationary

Answer: C (Less than g downwards)

Question 4: In a solenoid, if number of turns is doubled, then self inductance will become

1. Half
2. Double
3. 1 / 4 times

Question 5: According to Lenz’s law of electromagnetic induction

1. The relative motion between the coil and the magnet produces change in magnetic flux
2. The direction of induced emf is such that it supports the change in magnetic flux
3. Only the coil should be moved towards the magnet for production of induced emf
4. Only the magnet should be moved towards coil for the generation of  induced electric field

Answer: A ( The relative motion between the coil and the magnet)

Question 6: A horizontal conducting rod 10 m long extending from east to west is falling with speed 5 ms-1 at right angles to horizontal component of the earth’s magnetic field 0.3 x 10-4 wbm-2. Find the instantaneous value of emf induced in the coil.

1. 15 x 10-3 V
2. 1.5 x 10-3 V
3.  0.3 x 10-4
4. None of these

Answer: B ( 1.5 x 10-3 V )

Question 7: A magnet is moved towards a coil i) speedly  ii) slowly then induced emf/ induced charge will be respectively

1. More in first case / more in first case
2. More in first case / equal in both cases
3. Less in first case / more in second case
4. Less in first case / equal in both cases

Answer: B ( More in first case / equal in both cases )

Question 8: The magnetic flux linked with the coil, in Webers, is given by the equation Φ = 3 t2 + 4 t + 9 . Then the magnitude of induced emf at time t=2 s will be

1. 2 V
2. 4 V
3. 8 V
4. 16 V

Question 9: Lenz’s law is in accordance with law of conservation of

1. Charge
2. Momentum
3. Energy
4. Current

Question 10: What is increased in step down transformer?

1. Voltage
2. Current
3. Power
4. Current density

Question 11: In a transformer, number of turns in the primary coil are 140 and that in the secondary coil are 280. If current in primary is 4 A then that in secondary is

1. 4 A
2. 2 A
3. 6 A
4.  10 A

Question 12: An inductor L , a resistance R and two identical bulbs B1 and B2 are connected to a battery through a switch as as shown below. Which of the following statements gives the correct description of the happenings when the switch S is closed? 1. The bulb B2 lights up earlier than B1 and finally both the bulb shine equally bright
2. B1 lights up earlier and finally both the bulbs acquire equal brightness
3. B2 lights up earlier and finally B1 shines brighter than B2
4. B1 and B2 light up together with equal brightness all the time

Answer : C (B2 lights up earlier and finally B1 shines brighter than B2)

Question 13: Which one of the following is a correct statement?

1. Electric field is always conservative
2. Electric field due to a varying magnetic field is conservative
3. Electric field is conservative due to electrostatic charges while non-conservative due to a time varying magnetic field
4. Electric field lines are always closed loops

Answer : C (Electric field is conservative due to electrostatic charges while non-conservative due to a time varying magnetic field)

Question 14 : Eddy currents are produced when

1. A metal is kept in varying magnetic field
2. A metal is kept in a steady magnetic field
3. A circular coil is placed in a magnetic field
4. Through a circular col current is passed

Answer : A (A metal is kept in varying magnetic field)

Question 15: The core used in a transformer and other  electromagnetic devices is laminated so that

1. Ratio of voltage in the primary and secondary may be increased
2. Energy loss due to Eddy currents may be minimised
3. The weight of the transformer may be reduced
4. Residual magnetism in the core may be reduced

Answer : B (Energy loss due to Eddy currents may be minimised)

Question 16: Two coils X and Y are placed in a circuit such that when the current changes by 2 A in the coil X the magnetic flux changes by 0.4 Wb in Y. The value of mutual inductance of the coils is

1. 0.2 H
2. 5 H
3. 0.8 H
4. 4 H

Question 17: A metal ring is attached with the wall of a room. When the north pole of as magnet is brought near it, the induced current in the current will be 1. First clockwise then anticlockwise
2. In clockwise direction
3. In anticlockwise direction
4. First clockwise and then anticlockwise

Answer : C (In anticlockwise direction)

Question 18: In the given figure, current from A to B is decreasing. The direction of induced current in the loop is 1. Clockwise
2. Anticlockwise
3. Changing
4. Nothing can be said

Question 19: Induction furnace is based on the principle of

1. Self induction
2. Mutual induction
3. Eddy current
4. None of these

Question 20: When the plane of the armature of an a.c. generator is parallel to the field, in which it is rotating

1. Both the flux linked and emf induced in the coil are zero
2. The flux linked with it is zero, while induced emf is maximum
3. Flux linked is maximum while induced emf is zero
4. Both the flux linked and emf have their respective maximum values

Answer : B ( The flux linked with it is zero, while induced emf is maximum )

Question 21: Two circular coils can be arranged in any of the three ways as shown below. Their mutual inductance will be 1. Maximum in situation (i)
2. Maximum in situation (ii)
3. Maximum in situation (iii)
4. Same in all situations

Answer : A ( Maximum in situation (i) )

Question 22: A coil having 500 square loops each of side 10 cm is placed normal to a magnetic flux which increases at the rate of 1.0 T/s. The induced emf in volts is

1. 0.1
2. 0.5
3. 1
4. 5

Question 23: Two different loops are concentric and lie in the same plane. The current in the outer loop is clockwise and increasing with time. The induced current in the inner loop the, is

1. Clockwise
2. Zero
3. Counter clockwise
4. In a direction that depends on the ratio of loop radii

Question 24: Two coils of self inductance 2 mH and 8 mH are placed so close together that the effective flux in one coil is completely linked with the other. The mutual inductance between these coils are

1. 16 mH
2. 10 mH
3. 6 mH
4. 4 mH

Question 25: The energy stored in coil carrying current I is U. If current is halved, then energy stored in the coil will be

1. U / 2
2. U / 4
3. 2 U
4. 4 U

Answer : B (U / 4)

Question 26: The number of turns in the coil of an ac generator is 5000 and the area of the coil is 0.25 m. The coil is rotated at the rate of 100 cycles/ sec in a magnetic field of 0.2 Wb/m2. The peak value of the emf generated is nearly

1. 786 kV
2. 440 kV
3. 220 kV
4. 157.1 kV

Question 27: The frequency of an ac generator is altered with change in

1. Speed or rotation of coil
2. Amplitude of a.c.
3. Size of coil
4. All of the above

Answer : A (Speed or rotation of coil)

Question 28: The coefficient of mutual induction between two circuits is equal to the, emf produced in one circuit when current in second circuit is

1. Kept steady at 1 A
2. Cut – off at 1 A level
3. Changed at the rate of 1 A / s
4. Changed from 1 A/s to 2 A/s

Answer : C (Changed at the rate of 1 A/s)

Question 29: Consider the following statements
A) An EMF can be induced by moving a conductor in a magnetic field
B) An EMF can be induced by changing the magnetic field

1. Both A and B are true
2. A is true but B is false
3. B is true but A is false
4. Both A and B are false

Answer : A ( Both A and B are true)

Question 30: A metallic rod of 1 m length is rotated with a frequency of 50 revolution per second, with one end hinged at the centre and the other end at the circumference of a circular metallic ring of radius 1 m about an axis passing through the centre and perpendicular to the plane of the ring. A constant uniform magnetic field of 1 T parallel to the axis is present everywhere. The emf between the centre and the metallic ring is

1. 157 V
2. 117 V
3. 127 V
4. 137V

Question 31: Two different coils have self-inductances L1=8 mH and L2 =2 mH. The current in one coil is increased at a constant rate. The current in second coil is also increased at the same constant rate. At certain instant of time, the power given to the coils is the same. At that time, the current, the induced voltage and the energy stored in the first coil are i1, V1, and W1 respectively. Corresponding values for the second coil at the same instant are i2 , V2 and W2 respectively. Then choose the wrong option.

1.  i1 / i2 = 1 / 4
2. i1 / i2 = 4
3. W1 / W2 = 1 / 4
4. V1 / V2 = 1/ 4

Answer : B ( i1 / i2 = 4 )

Question 32: The working of generator is based upon

1. Magnetic effect of current
2. Heating effect of current
3. Chemical effect of current
4. Electromagnetic induction

Question 33: The self inductance L of a solenoid of length l and area of cross section A, with a fixed number of turns N increases as

1. l and A increases
2. l decreases and A increases
3. l increases and A decreases
4. Both l and A decreases

Answer : B ( l decreases and A increases )

Question 34: Which of the following does not use the application of eddy current?

1. Electric power meters
2. Induction furnace
3. LED lights
4. Magnetic brakes in trains

Question 35: The coefficient of mutual induction depends on

1. Medium between the coils
2. Distance between the coils
3. Orientation of the two coils
4. All of these

Answer : D (All of these)

Question 36: A copper rod of length l rotates about its end with angular velocity ω in a uniform magnetic field B. The emf developed between the ends of the rod if the field is normal to the plane of rotation is

1. Bωl2
2. 1/2  Bωl2
3. 2 Bωl2
4. 1/4 Bωl2

Answer : B ( 1/2  Bωl2 )

Question 37: A coil and a bulb are connected in series with a dc source, a soft iron core is inserted in the coil, then

1. Intensity of the bulb remains the same
2. Intensity of the bulb decreases
3. Intensity of the bulb increases
4. The bulb ceases to glow

Answer : B (Intensity of the bulb decreases)

Question 38: Two particles each of mass m and charge q are attached to the ends of a light rigid rod of length 2R. The rod is rotated at constant angular speed about a perpendicular axis passing through its centre. The ratio of magnetic moment of the system and its angular moment about the centre of rod is

1. q / 2m
2. q / m
3. 2q / m
4. q / πm

Answer : A (q / 2m)

Question 39: The transformation ratio in the step up transformer is

1. 1
2. Greater than one
3. Less than one
4. The ratio greater or less than one depends on the other factors

Answer : B [ (Greater than one)]

Question 40: The mutual inductance between a primary and secondary circuits is 0.5 H. The resistance of the primary and secondary circuits are 20 ohm and 5 ohm respectively. To generate a current of 0.4 A in secondary, current in primary must be changed at rate of

1. 4.0 A/s
2. 1.6 A/s
3. 16.0 A/s
4. 8.0 A/s

Question 41: A wheel with ten metallic spokes each 0.50 m long is rotated with a speed of 120 rev/min in a plane normal to the earth’s magnetic field at the plane. If the magnitude of the field is 0.4 G, the induced emf between the axle and the rim of the wheel is equal to

1. 1.256 x 10-3 V
2. 6.28 x 10 -4 V
3. 1.256 x 10 -4 V
4. 6.28 x 10-5 V

Answer : D ( 6.28 x 10-5 V )

Question 42: An a.c. generator consists of coil of 200 turns and cross sectional area of 3 m2, rotating at a constant angular speed of 60 radian / sec in a uniform magnetic field of 0.04 T. the resistance of the coil is 500 ohm. What is the maximum power dissipated in the coil?

1. 518.4 W
2. 1036 W
3. 259.2 W
4. Zero

Question 43: A long solenoid has a inductance L and resistance R. It is broken into two equal parts and then joined in parallel. The combination is joined to cell of emf E. The time constant for the circuit will be

1. L / 4 R
2. 2 L / R
3. L / R
4. L / 2 R

Answer : C ( L / R)

Question 44: A circular coil expands radially in a region of magnetic field and no electromotive force is produced in the coil. This is because

1. The magnetic field is constant
2. The magnetic field is in the same plane as the circular coil and it may or may not vary
3. The magnetic field has a perpendicular (to the plane of the coil) component whose magnitude is decreasing suitably
4. Both B and C are correct

Answer : D (Both B and C are correct)

Question 45: A long horizontal metallic rod with length along the east-est direction is falling under gravity. The potential difference between its two ends will

1. Be zero
2. Be constant
3. Increase with time
4. Decrease with time

Answer : C (Increase with time)

Question 46: A metal conductor of length 1 m rotates vertically about one of its end with angular velocity 5 rad s-1. If horizontal component of earth’s magnetic field is 0.2 x 10 -4 T, then the emf developed between the ends of the conductor is

1. 5 µ V
2. 5 mV
3. 50 µ V
4. 50 m V

Answer : C ( 50 µV)

Question 47: In a coil current falls from 5A to 0A in 0.2 s. If an average emf of 150 V is induced, then the self inductance of the coil is

1. 4 H
2. 2 H
3. 3 H
4. 6 H

Answer : D ( 6 H)

Question 48: An infinitely long cylinder is kept parallel to a uniform magnetic field B directed along positive z axis. The direction of induced current on the surface of cylinder as seen from the z axis will be

1. Clockwise of the positive z axis
2. Anticlockwise of the positive z axis
3. Zero
4. Along the magnetic field

#### MCQ of Alternating Current

Question 1: In an AC circuit containing only capacitance, the current

1. Leads the voltage by 180º
2. Remains in phase with voltage
3. Leads the voltage by 90º
4. Lags the voltage by 90º

Question 2: The resonant frequency of a circuit is f. If the capacitance is made 4 times the original value, then the resonant frequency will become

1. f / 2
2. 2 f
3. f
4. f / 4

Answer: A ( f / 2)

Question 3: In L-R circuit, resistance is 8 ohm and the inductive reactance is 6 ohm, then impedance is

1. 2 ohm
2. 14 ohm
3. 4 ohm
4. 10 ohm

Question 4: An inductance and a resistance are connected in series with an AC potential. In this circuit

1. The current and the potential difference across the resistance lead the PD across the resistance lead the PD across the inductance by phase angle π / 2
2. The current and the potential difference across the resistance lag behind PD across the inductance by angle π / 2.
3. The current and the potential difference across the resistance lag behind the PD across the inductance by an angle π.
4. The PD across the resistance lags behind the PD across the inductance by an angle π / 2 but the current in the resistance leads the potential difference across inductance by π / 2.

Answer: B ( The current and the potential difference across the resistance lag behind PD across the inductance by angle π / 2 )

Question 5: A 10 ohm resistance, 5 mH coil and 10 µF capacitor are joined in series. When a suitable frequency alternating current source is joined to this combination, the circuit resonates. If the resistance is halved, the resistance frequency

1. Is halved
2. Is doubled
3. Remains unchanged

Question 6: The peak value of AC voltage on a 220 V mains is

1. 240 √2 V
2. 230 √2 V
3. 220 √2 V
4. 200 √2 V

Question 7: Alternating current is transmitted at far off places

1. At high voltage and low current
2. At high voltage and high current
3. At low voltage and low current
4. At low voltage and high current

Answer: A (At high voltage and low current)

Question 8: When power is drawn from secondary coil of transformer, the dynamic resistance

1. Increases
2. Decreases
3. Remains unchanged
4. Changes electrically

Question 9: Transformer is based upon the principle of

1. Self induction
2. Mutual induction
3. Eddy current
4. None of these

Question 10: When an AC voltage is applied to a L-C-R circuit, which of the following is true?

1. I and V are out of phase with each other in R
2. I and V are in L with in C, they are out of phase
3. I and V are out of phase, in both L and C
4. I and V are out of phase in L and in phase in C

Answer: C (I and V are out of phase, in both L and C)

Question 11: The turns ratio of a transformer is given as 2 : 3. If the current through the primary coil is 3 A, thus calculate the current through load resistance

1. 1 A
2. 4.5 A
3. 2 A
4. 1.5 A

Question 12: A transformer is an electrical device used for

1. Producing direct current
2. Producing alternating current
3. Changing D.C into A.C.
4. Changing A.C. voltages

Question 13: Out of the following, choose the wrong statement:

1. A transformer cannot work on d.c.
2. A transformer cannot change the frequency of a.c.
3. A transformer can produce a.c. power
4. In a transformer, when a.c. voltage is raised n times, the alternating current reduces to 1/n time

Answer: C ( A transformer can produce a.c. power)

Question 14: High voltage transmission line is preferred as

1. Its appliances are less costly
2. Thin power cables are required
3. Idle current very low
4. Power loss is very less

Answer: D (Power loss is very less)

Question 15: In a purely resistive a.c. circuit, the current

1. Is in phase with the e.m.f.
3. Leads the e.m.f. by a phase difference of π / 2 radians
4. Lags behind the e.m.f. by a phase difference of π / 4 radians

Answer: A (Is in phase with the e.m.f. )

Question 16: In R-L-C series ac circuit, impedance cannot be increased by

1. Increasing frequency of the source
2. Decreasing frequency of the source
3. Increasing the resistance
4. Increasing the voltage of the source

Answer : D (Increasing the voltage of the source)

Question 17: Alternating current cannot be measured by DC ammeter, because

1. AC cannot pass through DC ammeter
2. AC changes direction
3. Average value of current for complete cycle is zero
4. DC ammeter will get damaged

Answer : C (Average value of current for complete cycle is zero)

Question 18: In a transformer the number of turns of primary and secondary coil are 500 and 400 respectively. If 200 V a.c. is supplied to the primary coil, then ratio of currents in primary and secondary coils is

1. 4 : 5
2. 5 : 4
3. 5 : 9
4. 9 : 5

Answer : A (4 : 5)

Question 19: A battery of 12 volt is connected to primary of a transformer with turns ratio ns / np = 10. Voltage across secondary would be

1. 120 V
2. 1.2 V
3. 12 V
4. Zero

Question 20: The reactance of capacitor with capacitance C is X. If both frequency and the capacitance become double then a new reactance will be

1. X
2. 2 X
3. 4 X
4. X / 4

Answer : D (X / 4)

Question 21: A power transmission line feeds input power at 2300 V to a step down transformer with its primary windings having 4000 turns, giving the output power at 230 V ,if the current in the primary of the transformer is  5 A, and its efficiency is 90%, the output current would be

1. 50 A
2. 25 A
3. 45 A
4. 20 A

Question 22: In an alternating current circuit consisting of elements in series the current increases on increasing the frequency of supply. Which of the following elements are likely to constituted the circuit?

1. Only resistor
2. Resistor and inductor
3. Resistor and capacitor
4. Only inductor

Answer : C (Resistor and capacitor)

Question 23: In which of the following circuits the maximum power dissipation is observed?

1. Pure capacitive circuit
2. Pure inductive circuit
3. Pure resistive circuit
4. None of these

Answer : C (Pure resistive circuit)

Question 24 : A pure resistive circuit element X when connected to an AC supply of peak voltage 200 V gives a peak current of 5 A which is in phase with the voltage. A second circuit element Y when connected to the same AC supply also gives the same value of peak current but the current lags behind by 90°. If the series combination of X and Y is connected to the same supply, what will be the rms value of the current?

1. 10 / √2 A
2. 5 / √ 2 A
3. 5 / 2 A
4. 5 A

Answer : C ( 5 / 2 A)

Question 25: At resonance frequency the impedance in series LCR circuit is

1. Maximum
2. Minimum
3. Zero
4. Infinity

Question 26: In a pure capacitive circuit if the frequency of AC source is doubled then its capacitive reactance will be

1. Remains same
2. Doubled
3. Halved
4. Zero

Question 27: The loss of energy in the form of heat in the iron core of transformer is

1. Iron loss
2. Copper loss
3. Mechanical loss
4. None of these

Question 28: A small town with a demand of 800 kW of electric power at 220 V is situated 15 km away from an electric plant generating power at 440 V. The resistance of the two wire line carrying power is 0.5 ohm per km. The town gets power from the line through a 4000 – 220 V step down transformer at a substation in the town. The line power loss in the form of heat is

1. 400 kW
2. 600 kW
3. 300 kW
4. 800 kW

Question 29: A series L C R circuit with R = 22 ohm, L = 1.5 H and C = 40 uF is connected to a variable frequency 220 V ac supply. When the frequency of the supply equals the natural frequency of the circuit, what is the average power transferred to the circuit in one complete cycle ?

1. 2000 W
2. 2200 W
3. 2400 W
4. 2500 W

Question 30: In highly inductive load circuit, it is more dangerous when

1. We close the switch
2. Open the switch
3. Increasing the resistance
4. Decreasing the resistance

Question 31: A transformer consisting of 300 turns in the primary and 150 turns in the secondary gives output power of 2.2 kW. If the current in the secondary coil is 10 A then the input voltage and current in the primary coil are

1. 440 V and 20 A
2. 440 V and 5 A
3. 220 V and 10 A
4. 220 V and 20 A

Answer : B (440 V and 5 A)

Question 32: An alternating voltage is connected in series with a resistance R and an inductance L .If the potential drop across the resistance is 200 V and across the inductance is 150 V ,then the applied voltage is

1. 350 V
2. 250 V
3. 500 V
4. 300 V

Question 33: An ideal choke takes a current of 8 A when connected to an AC source of 100 V and 50 Hz. A pure resistor under the same condition takes a current of 10 A. If two are connected in series to an AC supply of 100 V and 40 Hz then the current in the series combination of above resistor and inductor is

1. 10 A
2. 5 A
3. 5√2 A
4. 10√2 A

Question 34: In an L-C-R series AC circuit at resonance

1. The capacitive reactance is more than the inductive reactance
2. The capacitive reactance equals the inductive reactance
3. The capacitive reactance is less than the inductive reactance
4. The power dissipated is minimum

Answer: B (The capacitive reactance equals the inductive reactance)

Question 35: A choke is preferred to a resistance for limiting current in AC circuit because

1. Choke is cheap
2. There is no wastage of power
3. Choke is compact in size
4. Choke is good absorber of heat

Answer: B (There is no wastage of power)

Question 36: A 50 Hz AC source of 20 V is connected across R and C. The voltage across R is 12 V. The voltage across C will be

1. 8 V
2. 16 V
3. 10 V
4. Not possible to determine unless values of R and C are given

Question 37: Alternating voltage V = 140 sin 50 t is applied to a resistor of 10 ohm. This voltage produces heat in the resistor in the time t. To produce the same heat in the same time required DC current is

1. 14 A
4. None of these

Question 38: A virtual current of 4 A and 50 Hz flows in an AC circuit containing a coil. The power consumed in the coil is 240 W. If the virtual voltage across the coil is 100 V. Its inductance will be

1. 1 / 3π H
2. 1 / 5π H
3. 1 / 7π H
4. 1 / 9π H

Answer: B (1 / 5π H)

We would love your reading of MCQs for CUET 2022 of other subjects which are as follow.

# MCQ of Physics CUET

# MCQ of Physics CUET with Answers

# MCQ of Physics CUET 2022

# MCQ of Physics CUET 2023

# MCQ of Physics CUET Expected Questions

# MCQ of Physics CUET Expected Question with Answers

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