# MCQ of Electric Charges and Fields | Chapter 1 | Physics | Class 12 |

MCQ of Electric Charges and Fields, Chapter 1, Class 12, Physics

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

You may also go through other subjects like MCQs of Biology, Physics, Chemistry, Music, Accountancy, Business Studies, Economics, Geography, Political Science, Physical Education & English for Class 12 in order to have a strong hold on the subject with an intent to score higher in the first term examination.

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 )

You may also read MCQ of Electrostatic Potential and Capacitance, MCQ of Current Electricity, MCQ of Moving Charges and Magnetism, MCQ of Magnetism and Matter, MCQ of Electromagnetic Induction, MCQ of Alternating Current for better understanding of the chapters.

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 )

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