MCQ of Units and Measurements | Chapter 2 | Physics | Class 11 | CBSE |

MCQ of Units and Measurements Chapter 2, Physics, Class 11

Question 1: The units that are used for the fundamental physical quantities are called

1. System of unit
2. Base units
3. Derived units
4. All  of these

Answer : B (Base units)

Question 2: Which of the following physical quantities have same unit in all three system of units?

1. Mass
2. Length
3. Time
4. None of these

Answer: C (Time)

Question 3: Which one of the following physical quantities is not a fundamental quantity?

1. Luminous intensity
2. Thermodynamics temperature
3. Electric current
4. Work

Answer: D (Work)

Question 4: Which one of the following statements is incorrect ?

1. Direct and indirect method are used for the measurement of physical quantities
2. Scientific notations and the prefixes are used to simplify numerical computation
3. A dimensionally correct equation need not to be a correct equation
4. The SI units is based on six base units

Answer: D (The SI units is based on six base units)

Question 5: Which of the following is unitless quantity?

1. Pressure gradient
2. Displacement gradient
3. Velocity gradient
4. Force gradient

Answer: B (Displacement gradient)

Question 6: The value of universal gravitational constant G = 6.67 x 10-11 Nm²kg^-2. The value of g in units of g^-1 cm³ s^-2

1. 6.67 × 10^-8
2. 6.67 × 10^-7
3. 6.67 × 10^-9
4. 6.67 × 10^-10

Answer: A (6.67 × 10^-8)

Question 7: Which of the following is not unit of length ?

1. Angstrom
2. Fermi
3. Barn
4. Parsec

Answer: C (Barn)

Question 8: Which of the following is the smallest unit?

1. Millimetre
2. Angstrom
3. Fermi
4. Metre

Answer: C (Fermi)

Question 9: Which one of the following instrument is not used for the measurement of length?

1. Atomic clock
2. Vernier callipers
3. Screw gauge
4. Spherometer

Answer: A (Atomic clock)

Question 10: Light year is

1. Light emitted by the sun in one year
2. Time taken by light to travel from sun to earth
3. The distance travelled by light in free space in one year
4. The time taken by Earth to go once around the sun

Answer: C (The distance travelled by light in free space in one year)

You may also read MCQ of Physical World, MCQ of Motion in a Straight Line, MCQ of Motion in a Plane, MCQ of Laws of Motion, MCQ of Work, Energy and Power, MCQ of System of Particles and Rotational Motion, MCQ of Gravitation for better understanding of the chapters.

Question 11: Light year is the unit of

1. Distance
2. Time
3. Speed
4. Intensity of light

Answer: A (Distance)

Question 12: Which one of the following method is used to measure distance of of a planet or a star from the earth ?

1. Echo method
2. Parallax method
3. Triangulation method
4. None of these

Answer : B (Parallax method)

Question 13: The sun’s angular distance is measured to be 1920”. The distance of the sun from the earth is 1.496 × 10¹¹ m. What is the diameter of the Sun?

1. 1.39 × 10⁹ m
2. 1.39 × 10¹⁰ m
3. 1.39 × 10¹¹ m
4. 1.39 × 10¹² m

Answer: A (1.39 × 10⁹ m)

Question 14: What is the length of the arc of a circle of radius which subtends an angle π/6 at the centre ?

1. 11.7 cm
2. 14.7 cm
3. 16.7 cm
4. 15.7 cm

Answer: D (15.7 cm)

Question 15: The device used for measuring the mass of atoms and molecules is

1. Spring balance
2. Torsional balance
3. Mass spectrograph
4. Common balance

Answer: C (Mass spectrograph)

Question 16: If the error in measuring the radius of the sphere is 2% and that in measuring its mass is 3% , then the error in measuring the density of material of the sphere is

1. 5%
2. 7%
3. 9%
4. 11%

Answer: C (9%)

Question 17: Which of the following statements is incorrect ?

1. Every measurement by measuring instrument has same error
2. A measurement can have more accuracy but less precision and vice versa
3. Every calculated quantity that is based on measured values has some error
4. The magnitude of the difference between the true value of the quantity and the individual measurement value is called the relative error of the measurement.

Answer: D (The magnitude of the difference between the true value of the quantity and the individual measurement value is called the relative error of the measurement)

Question 18: Which of the following instruments has minimum least count?

1. A vernier callipers with 20 divisions on the vernier scale coinciding with 19 main scale division
2. A Screw goes of pitch 1 mm and 100 divisions on the circular scale
3. A spherometer of pitch 1 mm and 100 divisions on the circular scale
4. An optical instrument that can measure length to within a wavelength of length

Answer: D (An optical instrument that can measure length to within a wavelength of length)

Question 19 : Two resistors of resistances R₁ = (300 ± 3) ohm and R₂ = (500 ± 4)ohm are connected in series. The equivalent resistance of the series combination is

1. (800 ± 1) ohm
2. (800 ± 7) ohm
3. (200 ± 7) ohm
4. (200 ± 1) ohm

Answer : B ( (800 ± 7) ohm )

Question 20: Two resistors of resistances R1 = (100 ± 3) ohm and R2 = (200 ± 4)ohm are connected to parallel. The equivalent resistance of the parallel combination is 

1. (66.7 ± 1.8) ohm
2. (66.7 ± 4.0) ohm
3. (66.7 ± 3.0) ohm
4. (66.7 ± 7.0) ohm

Answer : A ( (66.7 ± 1.8) ohm)

Question 21: The period of oscillation of a simple pendulum is          T = 2π √L / g . Measured value of L is 10 cm known to 1 mm accuracy and time for 100 oscillation  of the pendulum is found to be 50 s using a wrist watch of 1 s revolution. What is accuracy in the determination of g ?

1. 2 %
2. 3 %
3. 4 %
4. 5 %

Answer : D (5 %)

Question 22: A physical quantity X is related to four measurable quantities a, b, c and d as given, X = a²b³c^5/2d^-2 . The percentage error in the measurement of a,b,c and d are 1%, 2%, 3% and 4% respectively. What is the percentage error in quantity X?

1. 15 %
2. 17 %
3. 21 %
4. 23 %

Answer : C ( 21 %)

Question 23: Which of the following statements is incorrect regarding significant figures?

1. All the non zero digits are significant.
2. All the zeros between two non zero digits are significant
3. Greater the number of significant figures in a measurement, smaller is the percentage error
4. The power of 10 is counted while counting the number of significant figures

Answer: D ( The power of 10 is counted while counting the number of significant figures )

Question 24: Which of the following physical quantities has a unit but no dimensions?

1. Relative velocity
2. Relative density
3. Strain
4. Angle

Answer: D (Angle)

Question 25: Which of the following physical quantities has neither units nor dimensions?

1. Relative velocity
2. Relative density
3. Angle
4. Energy

Answer: B (Relative density)

Question 26: A dimensionless quantity

1. Never has a unit
2. Always has unit
3. May have a unit
4. Does not exist

Answer: C (May have a unit)

Question 27: Which of the following pairs of physical quantities have same dimensions?

1. Force and power
2. Torque and energy
3. Torque and power
4. Force and torque

Answer: B (Torque and energy)

Question 28: Which of the following sets have different dimensions?

1. Pressure, Young’s modulus , stress
2. EMF , potential difference, electric potential
3. Heat, work done, energy
4. Dipole moment, electric flux, electric field

Answer: D (Dipole moment, electric flux, electric field)

Question 29: The dimensions of planck’s constant are the same as that of

1. Linear impulse
2. Work
3. Linear momentum
4. Angular momentum

Answer: D (Angular momentum)

Question 30: dimensional formula of ∆Q, heat supplied to the system is

1. [ML²T^-2]
2. [MLT^-2]
3. [ML²T^-1]
4. [MLT]

Answer: A ( [ML²T^-2] )

Question 31: The dimensional formula of a physical quantity is [M^aL^bT^c] . Then that physical quantity is

1. Surface tension if a =1, b=1, c=-2
2. Force if a=1, b=1, c=2
3. Angular frequency if a=0, b=0, c=-1
4. Spring constant if a=1, b=-1 , c=-2

Answer: C ( Angular frequency if a=0, b=0, c=-1 )

Question 32: Checking the correctness of equations using the method of dimensions is based on

1. The type of system
2. Equality of inertial frames of references
3. Principle of homogeneity of dimensions
4. None of these

Answer: C (Principle of homogeneity of dimensions)

Question 33: A new system of units is proposed in which unit of mass is α kg, unit of length is β m and unit of time is ϒ s. What will be value of 5 J in this system?

1. 5 α β² γ^-2
2. 5 α^-1 β^-2 γ²
3. 5 α^-2 β^-1 γ^-2
4.  5 α^-1 β² γ²

Answer: B (5 α^-1 β^-2 γ²)

Question 34: If the energy, E= G^p h^q c^r, where G is the universal gravitational constant, h is the planck’s constant and c is the velocity of light, then the values of p, q and r are, respectively 

1. -1/2, 1/2 and 5/2
2. 1/2, -1/2 and -5/2
3. -1/2, 1/2 and 3/2
4. 1/2, -1/2 and -3/2

Answer: A ( -1/2, 1/2 and 5/2 )

Question 35: The equation of state of a gas is given by ( P+ a / V³) (V -b²) = cT, where P,V,T are pressure, volume and temperature respectively and a,b,c are constants. The dimensions of a and b are respectively. 

1. [ML⁸T^-2] and [L^3/2]
2. [ML⁵T^-2] and [L³]
3. [ML⁵T^-2] and [L⁶]
4. [ML⁶T^-2] and [L^3/2]

Answer: A ( [ML⁸T^-2] and [L^3/2] )

Question 36: The velocity of a particle (v) at an instant t is given by v = at + bt² . The dimension of b is 

1. [L]
2. [LT^-1]
3. [LT^-2]
4. [LT^-3]

Answer: D ( [LT^-3] )

Question 37: The time period of oscillation of a body is given by       T= 2π √mgA / K ; K represents the kinetic energy, m mass, g acceleration due to gravity and A is unknown. If [A]= M^xL^yT^z; then what is the value of x + y + z?

1. 3
2. 2
3. 1
4. 5

Answer: A (3)

Question 38: A potential difference V = 100 ± 5 V, when applied across a resistance, gives a current I = 10 ± 0.2 A. What is the percentage error in R?

1. 2 %
2. 5 %
3. 7 %
4. 8 %

Answer: C (7 %)

Question 39: In an experiment , the percentage of error occurred in the measurement of physical quantities A, B , C and D are 1 %, 2 %, 3 % and 4% respectively. Then the maximum percentage of error in the measurement X, where X = A² B^1/2 / C ^1/3 D³, will be 

1. 10 %
2. 3 / 13 %
3. 16 %
4. -10 %

Answer: C (16 %)

Question 40: Dimensional formula for energy in terms of momentum (p), area (A) and time (T) is 

1. ρ²A²T^-1
2. ρ¹A^1/2T^-1
3. ρ^1/2A¹T^-1
4. ρ⁰A^-2T^-2

Answer: B (ρ¹A^1/2T^-1 )

Question 41: Suppose a quantity y can be dimensionally represented in terms of M, L and T, that is [y] = [M^aL^bT^c] then M

1. May be represented in terms of L, T and y if a = 0
2. May be represented in terms of L, T and y if a ≠ 0
3. Can always be dimensionally represented in terms of L, T and y
4. Can never be dimensionally represented in terms of L, T and y

Answer: B ( May be represented in terms of L, T and y if a ≠ 0 )

Question 42: Precision of measurement depends on

1. Least count of measuring instrument
2. Temperature of the surroundings
3. Carefulness of observer
4. All of the above

Answer: A ( Least count of measuring instrument )

Question 43: Given F= (a/t) + bt² where F denotes force and t time. The dimensions of a and b are respectively.

1. [MLT^-1] and [MLT^-4]
2. [LT^-1] and [T^-2]
3. [T] and [T^-2]
4. [LT^-2] and [T^-2]

Answer: A ( [MLT^-1] and [MLT^-4] )

Question 44: If units of length, mass and force are chosen at fundamental units, the dimensions of time would be :

1. M^1/2 L^-1/2 F^1/2
2. M^1/2 L^1/2 F^1/2
3. M^1/2 L^1/2 F^-1/2
4. M¹ L^-1/2 F^-1/2 

Answer: C (M^1/2 L^1/2 F^-1/2)

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