CBSE Class 11 Physics Units and Measurements MCQs Set B

Question: The dimensional formula of angular momentum is 
a) [ML²T^–2]
b) [ML^–2T^–1]
c) [MLT^–1]
d) [ML²T^–1].
Answer: d

Question: The unit of permittivity of free space, e₀, is 
a) coulomb/newton-metre
b) newton-metre²/coulomb²
c) coulomb²/newton-metre²
d) coulomb²/(newton-metre)²
Answer: c

Question: Planck’s constant (h), speed of light in vacuum c) and Newton’s gravitational constant (G) are three fundamental constants. Which of the following combinations of these has the dimension of length ?
a) √hG /c3/2
b) √hG /c5/2
c) √hc/G
d) √Gc/h3/2
Answer: a

Question: The unit of thermal conductivity is
a) W m^–1 K^–1
b) J m K^–1
c) J m^–1 K^–1
d) W m K^–1
Answer: a

Question: The dimensions of pressure is equal to
a) force per unit volume
b) energy per unit volume
c) force
d) energy
Answer: b

Question: The dimensions of Planck’s constant equals to that of 
a) energy
b) momentum
c) angular momentum
d) power.
Answer: c

Question: Which pair do not have equal dimensions ?
a) Energy and torque
b) Force and impulse
c) Angular momentum and Planck’s constant
d) Elastic modulus and pressure.
Answer: b

Question: The dimensions of impulse are equal to that of
a) pressure
b) linear momentum
c) force
d) angular momentum
Answer: b

Question: A screw gauge has least count of 0.01 mm and there are 50 divisions in its circular scale. The pitch of the screw gauge is
a) 0.01 mm
b) 0.25 mm
c) 0.5 mm
d) 1.0 mm 
Answer: c

Question: The dimension of 1/2 ε₀ E² ,where e0 is permittivity of free space and E is electric field, is
a) ML²T^–2
b) ML^–1T^–2
c) ML²T^–1
d) MLT^–1
Answer: b

Question: A student measured the diameter of a small steel ball using a screw gauge of least count 0.001 cm.
The main scale reading is 5 mm and zero of circular scale division coincides with 25 divisions above the reference level. If screw gauge has a zero error of
–0.004 cm, the correct diameter of the ball is
a) 0.521 cm
b) 0.525 cm
c) 0.053 cm
d) 0.529 cm 
Answer: d

Question: [MLT^–1] + [MLT^–1] = ............. B
a) [M°L°T°]
b) [MLT^–1]
c) 2[MLT^–1]
d) None of the options
Answer: b

Question: In an experiment, four quantities a, b, c and d are measured with percentage error 1%, 2%, 3% and 4% respectively. Quantity P is calculated as follows
P a3b2 /cd . % error in P is
a) 7%
b) 4%
c) 14%
d) 10%
Answer: c

Question: Dimensions of stress are
a) [MLT^–2]
b) [ML²T^–2]
c) [ML⁰T^–2]
d) [ML^–1 T^–2] 
Answer: d

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) 12%
b) 14%
c) 7%
d) 9%. 
Answer: d

Question: The dimensional formula of angular velocity is
a) [MLT^–1]
b) [M⁰L⁰T]
c) [ML⁰T^–2]
d) [M⁰L⁰T^–1]
Answer: d

Question: The dimensions of universal gravitational constant are 
a) [M^–1L³T^–2]
b) [ML²T^–1]
c) [M^–2L³T^–2]
d) [M^–2L²T^–1] 
Answer: a

Question: Which of the following dimensions will be the same as that of time? 
a) L /R
b) C /L
c) LC
d) R /L
Answer: a

Question: The damping force on an oscillator is directly proportional to the velocity. The units of the constant of proportionality are 
a) kg m s^–1
b) kg m s^–2
c) kg s^–1
d) kg s
Answer: c

Question: Taking into account of the significant figures, what is the value of 9.99 m – 0.0099 m?
a) 9.9801 m
b) 9.98 m
c) 9.980 m
d) 9.9 m
Answer: b

Question: 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 = A2B1/2 /C1/3D3 will be
a) 10%
b) (3/13)%
c) 16%
d) –10%
Answer: c

Question: The pair of quantities having same dimensions is
a) Impulse and Surface Tension
b) Angular momentum and Work
c) Work and Torque
d) Young’s modulus and Energy
Answer: c

Question: If the dimensions of a physical quantity are given by MaLbTc, then the physical quantity will be
a) velocity if a = 1, b = 0, c = – 1
b) acceleration if a = 1, b = 1, c = – 2
c) force if a = 0, b = – 1, c = – 2
d) pressure if a = 1, b = –1, c = –2
Answer: d

Question: If force (F), velocity (V) and time (T) are taken as fundamental units, then the dimensions of mass are
a) [FVT^–1]
b) [FVT^–2]
c) [FV^–1T^–1]
d) [FV^–1T]
Answer: d

Question: The density of a material in CGS system of units is 4 g cm^–3. 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) 0.04
b) 0.4
c) 40
d) 400
Answer: c

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^–2]
b) [ML²T^–1I^–1]
c) [ML²T^–3I^–2]
d) [ML²T^–3I^–1]
Answer: b

Question: If dimensions of critical velocity vc of a liquid flowing through a tube are expressed as [hxryrz] where h, r and r are the coefficient of viscosity of liquid, density of liquid and radius of the tube respectively, then the values of x, y and z are given by 
a) –1, –1, –1
b) 1, 1, 1
c) 1, –1, –1
d) –1, –1, 1
Answer: c

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: a

Question: An equation is given here (p + a/v²) = b.Θ/V where P = Pressure, V = Volume and q = Absolute temperature. If a and b are constants, the dimensions of a will be 
a) [ML^–5T^–1]
b) [ML⁵T¹]
c) [ML⁵T^–2]
d) [M^–1L⁵T²].
Answer: c

Question: A certain body weighs 22.42 g and has a measured volume of 4.7cc. The possible error in the measurement of mass and volume are 0.01 g and 0.1 cc. Then maximum error in the density will be
a) 22% 
b) 2%
c) 0.2%
d) 0.02%.
Answer: b

Question: If C and R denote capacitance and resistance, the dimensional formula of CR is
a) [M⁰L⁰T¹]
b) [M⁰L⁰T⁰]
c) [M⁰L⁰T^–1]
d) not expressible in terms of MLT.
Answer: a

Question: Turpentine oil is flowing through a tube of length l and radius r. The pressure difference between the two ends of the tube is P. The viscosity of oil is given by η= P(r² - x²) / 4vl where v is the velocity of oil at a distance x from the axis of the tube. The dimensions of h are 
a) [M⁰L⁰T⁰]
b) [MLT^–1]
c) [ML²T^–2]
d) [ML^–1T^–1]
Answer: d

Question: The dimensions of (μ₀ε₀)^–1/2 are
a) [L¹/2T^–1/2]
b) [L^–1T]
c) [LT^–1]
d) [L¹/2T^1/2]
Answer: c

Question: The dimensional formula of torque is 
a) [ML²T^–2]
b) [MLT^–2]
c) [ML^–1T^–2]
d) [ML^–2T^–2].
Answer: a

Question: The ratio of the dimensions of Planck’s constant and that of moment of inertia is the dimensions of
a) time
b) frequency
c) angular momentum
d) velocity.
Answer: b

Question: The main scale of a vernier callipers has n divisions/cm. n divisions of the vernier scale coincide with (n – 1) divisions of main scale. The least count of the vernier callipers is
a) 1 /(n+1)(n-1)cm
b) 1/n cm
c) 1/n² cm
d) 1 /n(n + 1) cm
Answer: c

Question: Of the following quantities, which one has dimensions different from the remaining three ?
a) Energy per unit volume
b) Force per unit area
c) Product of voltage and charge per unit volume
d) Angular momentum.
Answer: d

Question: Dimensional formula of self inductance is 
a) [MLT^–2A^–2]
b) [ML²T^–1A^–2]
c) [ML²T^–2A^–2]
d) [ML²T^–2A^–1]
Answer: c

Question: The time dependence of a physical quantity p is given by p = p0 exp (–at²), where a is a constant and t is the time. The constant a
a) is dimensionless
b) has dimensions [T^–2]
c) has dimensions [T²]
d) has dimensions of p
Answer: b

Question: The dimensions of RC is 
a) square of time
b) square of inverse time
c) time
d) inverse time.
Answer: c

Question: Which of the following has the dimensions of pressure?
a) [MLT^–2]
b) [ML^–1T^–2]
c) [ML^–2T^–2]
d) [M^–1L^–1]
Answer: b

Question: A student measures the distance traversed in free fall of a body, initially at rest, in a given time. He uses this data to estimate g, the acceleration due to gravity. If the maximum percentage errors in measurement of the distance and the time are e1 and e2 respectively, the percentage error in the estimation of g is 
a) e₂ – e₁
b) e₁ + 2e₂
c) e₁ + e₂
d) e₁ – 2e₂
Answer: b

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) 8%
b) 2%
c) 4%
d) 6% 
Answer: d

Question: The velocity v of a particle at time t is given by v=at + b/t+c where a, b and c are constants. The dimensions of a, b and c are
a) [L], [LT] and [LT^–2]
b) [LT^–2], [L] and [T]
c) [L²], [T] and [LT^–2]
d) [LT^–2], [LT] and [L].
Answer: b

Question: The dimensional formula of permeability of free space m0 is
a) [MLT^–2A^–2]
b) [M⁰L¹T]
c) [M⁰L²T^–1A²]
d) None of the options.
Answer: a

Question: According to Newton, the viscous force acting between liquid layers of area A and velocity gradient Δv/ΔZ is given by F = -ηA Δv /ΔZ where h is constant called coefficient of viscosity. The dimensional formula of h is
a) [ML^–2T^–2]
b) [M⁰L⁰T⁰]
c) [ML²T^–2]
d) [ML^–1T^–1].
Answer: d

Question: Which of the following is a dimensional constant?
a) Relative density
b) Gravitational constant
c) Refractive index
d) Poisson’s ratio
Answer: b

Question: The dimensional formula of magnetic flux is
a) [M⁰L^–2T^–2A^–2]
b) ML⁰T^–2A^–2]
c) [ML²T^–2A^–1]
d) [ML²T^–1A³]
Answer: c

Question: Which two of the following five physical parameters have the same dimensions ?
1. energy density
2. refractive index
3. dielectric constant
4. Young’s modulus 5. magnetic field
a) 1 and 4
b) 1 and 5
c) 2 and 4
d) 3 and 5 
Answer: a