JEE Physics Units and Measurements MCQs Set C

Question: Which pair do not have equal dimensions?

• a) Force and impulse
• b) Elastic modulus and pressure
• c) Energy and torque
• d) Angular momentum and Planck’s constant

Answer: Force and impulse

Question: The dimensions of Planck’s constant equals to that of

• a) Angular momentum
• b) Power
• c) Momentum
• d) Energy

Answer: Angular momentum

Question: The dimensions of universal gravitational constant are

• a) [M^–1L³T^–2]
• b) [ML²T^–1]
• c) M^–2L3T^–2]
• d) M^–2L3T^–3]

Answer: [M^–1L³T^–2]

Question: The ratio of the dimensions of Planck’s constant and that of moment of inertia is the dimension of

• a) Frequency
• b) Time
• c) Angular momentum
• d) Velocity

Answer: Frequency

Question:

• a) LT ^–2, L and T
• b) L, LT and LT ^–2
• c) L², T and LT²
• d) LT², LT and L

Answer: LT ^–2, L and T

Question: Dimensions of resistance in an electrical circuit, in terms of dimension of mass M, of length L, of time T and of current I, would be

• a) [ML²T^–3I^–2]
• b) [ML²T^–3I^–1]
• c) [ML²T^–1I^–1]
• d) [ML²T^–2]

Answer:  [ML²T^–3I^–2]

Question: If the dimensions of a physical quantity are given by MaLbTc, then the physical quantity will be

• a) Pressure if a = 1, b = –1, c = –2
• b) Acceleration if a = 1, b = 1, c = –2
• c) Velocity if a = 1, b = 0, c = –1
• d) Force if a = 0, b = –1, c = –2

Answer: Pressure if a = 1, b = –1, c = –2

Question:

• a) ML^–1T^–2
• b) ML²T^–1
• c) ML²T^–2
• d) MLT^–1

Answer: ML^–1T^–2

Question:

A : Out of the measurements A = 20.00 and B = 20.000, B is more accurate.

R : Percentage error in B is less than the percentage error in A.

• a) A is correct and R is wrong 
• b) R is correct and A is wrong 
• c) Both are correct
• d) Both are wrong

Answer: A is correct and R is wrong 

Question:

A : When we change the unit of a measurement of a quantity, its numerical value changes.

R : The product of numerical value of the physical quantity and unit for a quantity remain constant

• a) A is correct and R is wrong
• b) R is correct and A is wrong
• c) Both are correct
• d) Both are wrong

Answer: A is correct and R is wrong

Question:

• a) m^2, ms^–2
• b) m, ms^–1
• c) m², m
• d) All of these

Answer:  m^2, ms^–2

Question:

• a)

  

• b)

  

• c)

  

• d) All of these

Answer:

Question:

• a) Angle
• b) Time
• c) Length
• d) Mass

Answer: Angle

Question: Let P represent radiation pressure, c represent speed of light and I represent radiation energy striking a unit area per second, then PxI ycz will be dimensionless for

• a) x = z = –y
• b) x = y = –z
• c) x = y = z
• d) x = 0, y = z

Answer:  x = z = –y

Question:

• a) [M⁰L²T^–1]
• b) [M⁰L²T²]
• c) [M⁰L^–1T^–1]
• d) [M⁰L^–1T²]

Answer: [M⁰L²T^–1]

Question:  The frequency of vibrations f of a mass m suspended from a spring of spring constant K is given by a relation of type f = cm^xK^y, where c is a dimensionless constant. The values of x and y are

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: If energy E, velocity V and time T are taken as fundamental units, the dimensional formula for surface tension is

• a) [EV^–2T^–2]
• b) [E^–2VT^–2]
• c) [E^–2VT^–1]
• d) All of these 

Answer: [EV^–2T^–2]

Question: If force F, area A and density D are taken as the fundamental units, the representation of Young’s modulus ‘Y’ will be

• a) [FA^–1D⁰]
• b) None of this
• c) [FA^–1D]
• d) [FA^–2D²]

Answer:  [FA^–1D⁰]

Question: If velocity, time and force (V, T & F) are considered as fundamental quantities, the dimensional formula for mass will be

• a) [FTV^–1 ]
• b) [FT^–1V ]
• c) [F^–1TV ]
• d) [FTV]

Answer: [FTV^–1 ]

Question: If the error in the measurement of radius of a sphere is 2%, then the error in the determination of volume of the sphere will be

• a) 6%
• b) 8%
• c) 4%
• d) 2%

Answer: 6%

Question: Percentage errors in the measurement of mass and speed are 2% and 3% respectively. The error in the estimate of kinetic energy obtained by measuring mass and speed will be

• a) 8%
• b) 2%
• c) 12%
• d) 10%

Answer:  8%

Question: The density of a cube is measured by measuring its mass and length of its sides. If the maximum error in the measurement of mass and lengths are 3% and 2% respectively, the maximum error in the measurement of density would be

• a) 9%
• b) 7%
• c) 14%
• d) 12%

Answer: 9%

Question:  A set of defective observation of weights is used by a student to find the mass of an object using a physical balance. A large number of readings will reduce

• a) Random error
• b) Random as well as systematic error
• c) Systematic error
• d) Neither random nor systematic error

Answer: Random error

Question: A force F is applied on a square area of side L. If the percentage error in the measurement of L is 2% and that in F is 4%, what is the maximum percentage error in pressure?

• a) 8%
• b) 6%
• c) 4%
• d) 2%

Answer: 8%

Question:  The radius of a sphere is (5.3 ± 0.1) cm. The percentage error in its volume is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:   If the percentage error in the measurement of momentum and mass of an object are 2% and 3% respectively, then maximum percentage error in the calculated value of its kinetic energy is

• a) 7%
• b) 5%
• c) 1%
• d) 2%

Answer: 7%

Question:

• a)

  

• b)

  

• c)

  

• d) None of this

Answer:

Question: A public park, in the form of a square, has an area of (100 ± 0.2) m². The side of park is

• a) (10 ± 0.01) m
• b) (10 ± 0.1) m
• c) (10 ± 0.02) m
• d) (10 ± 0.2) m

Answer:  (10 ± 0.01) m

Question:

• a)

  

• b)

  

• c)

  

• d) None of this

Answer:

Question:

• a) 0.8%
• b) 0.1%
• c) 1.8%
• d) 8%

Answer: 0.8%

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: The pair of quantities having same dimensions is

• a) Work and Torque
• b) Impulse and Surface Tension
• c) Young's modulus and Energy
• d) Angular momentum and Work

Answer: Work and Torque

Question: The damping force on an oscillator is directly proportional to the velocity. The units of the constant of proportionality are

• a) kgs^–1
• b) kgs
• c) kgms^–1
• d) kgms^–2

Answer: kgs^–1

Question:

• a) [LT^–1]
• b) [L^–1T]
• c) [L^1/2T^–1/2]
• d) [L^1/2T^1/2]

Answer: [LT^–1]

Question:

• a) [M¹L¹T^–2A^–2]
• b) [L^–1T]
• c) Both
• d) None of this

Answer: [M¹L¹T^–2A^–2]

Question: The density of a material in CGS system of units is 4 g/cm³. In a system of units in which unit of length is 10 cm and unit of mass is 100 g, the value of density of material will be

• a) 40
• b) 0.4
• c) 0.04
• d) 400

Answer: 40

Question: What is the dimension of surface tension?

• a) [ML⁰T^–2]
• b) [M¹L⁰T^–2]
• c) Both
• d) None of this

Answer: [ML⁰T^–2]

Question: Which two of the following five physical parameters have the same dimensions?

(a) Energy density (b) Refractive index

(c) Dielectric constant (d) Young’s modulus

(e) Magnetic field

• a) (a) and (d)
• b) (c) and (e)
• c) (b) and (d)
• d) (a) and (e)

Answer:  (a) and (d)

Question:

• a) 14%
• b) 4%
• c) 7%
• d) 10%

Answer: 14%

Question: If the error in the measurement of radius of a sphere is 2%, then the error in the determination of volume of the sphere will be

• a) 6%
• b) 8%
• c) 4%
• d) 2%

Answer: 6%

Question: Which of the following has the dimensions of pressure?

• a) [ML^–1T^–2]
• b) [M^–1L^–1]
• c) [MLT^–2]
• d) [ML^–2T^–2]

Answer: [ML^–1T^–2]

Question: Percentage errors in the measurement of mass and speed are 2% and 3% respectively. The error in the estimate of kinetic energy obtained by measuring mass and speed will be

• a) 8%
• b) 2%
• c) 12%
• d) 10%

Answer:  8%

Question: Which of the following is a dimensional constant?

• a) Gravitational constant
• b) Relative density
• c) Refractive index
• d) Poisson’s ratio

Answer: Gravitational constant

Question: The dimensions of RC is

• a) Time
• b) Inverse time
• c) Square of inverse time
• d) Square of time

Answer: Time

Question: The dimensions of impulse are equal to that of

• a) Linear momentum
• b) Pressure
• c) Force
• d) Angular momentum

Answer: Linear momentum

Question:   The density of a cube is measured by measuring its mass and length of its sides. If the maximum error in the measurement of mass and lengths are 3% and 2% respectively, the maximum error in the measurement of density would be

• a) 9%
• b) 7%
• c) 14%
• d) 12%

Answer: 9%

Question:

• a) [ML⁵ T^–2]
• b) [M^–1 L⁵T²]
• c) [ML⁵ T¹]
• d) All of these

Answer: [ML⁵ T^–2]

Question:  Which of the following dimensions will be the same as that of time?

• a)

  

• b)

  

• c)

  

• d) LC

Answer:

Question: The dimensional formula of magnetic flux is

• a) [ML²T^–2A^–1]
• b) [ML²T^–1A³]
• c) [ML⁰T^–2A^–2]
• d) All of these

Answer:  [ML²T^–2A^–1]