# Class 11th Physics – 2 Units and Measurements MCQs

#### The smallest mass measured so far is ____.

Correct! Wrong!

The smallest mass measured so far is that of an e- which is≈10-30k.

#### The order of mass of universe is ____.

Correct! Wrong!

The mass of universe is of the order 1055 kg.

#### Pascal is the SI unit of

Correct! Wrong!

Pascal is the SI unit of stress

#### The weight of a body is 30 gm. The statement made above is not correct because

Correct! Wrong!

Weight is a force. The unit of force is newton. Hence, weight should be expressed in newton.

#### If a screw gauge has 200 equal divisions marked along the circumference of the disc and one full rotation of the disc advances on the main scale by 0.05 cm, then the least count of the screw gauge is ____.

Correct! Wrong!

L.C = Pitch/No. of division in circular scale = 0.05/200 = 2.5 × 10-4 cm

#### If R is the distance of the moon from earth, θ the angle subtended by the moon at the earth, then D the diameter of the moon is given by

Correct! Wrong!

If R is the distance of the moon from earth, θ the angle subtended by the moon at the earth, then D the diameter of the moon is given by D = Rθ.

#### Which is most accurate significant figure among the given options ____.

Correct! Wrong!

3.000m because it has maximum no. of significance .

#### Which of the following system of units is not based on mass, length and time alone?

Correct! Wrong!

SI is based on seven basic units and two supplementary units.

#### Parallactic second is the largest unit of

Correct! Wrong!

One parallactic second is the distance corresponding to a parallax 3.26 light year (approx.).

#### The significant figure of 0.99 - 0.989 is ____.

Correct! Wrong!

0.99 - 0.989 = 0.001 = 0.01 × 10-1

#### If the dimensions of a rectangular block measured with callipers having least count of 0.01 cm are 5 mm ×10 mm × 5 mm, then the maximum percentage error in the measurement of volume will be ____.

Correct! Wrong!

% error = 0.01/0.5×100 + 0.01/1.0×100 + 0.01 /0.5×100 = 4 + 1 = 5 %

#### ___ is not a unit of length.

Correct! Wrong!

Options a, b & c are units of length while d is unit of angle in a plane.

#### If the diameter of a sphere is measured with an instrument having least count 0.001 cm, the diameter is 1.933 cm, then the radius to correct significant figures will be ____.

Correct! Wrong!

radius = diameter/2 = 1.933/2 = 0.9665 = 0.966 cm, this is according to the rule "rounding to even."

#### The dimensions of kinetic energy is ____.

Correct! Wrong!

M (L T-1)2 = M1 L2 T-2 ∵1/2 has no dimension

#### If pressure depends on distance, P =α/β exp( -αz/kϴ) where α, β are constants, z = distance, k = Boltzman's constant and θ = temp, then the dimension of β is ____.

Correct! Wrong!

Unit of k is joules per Kelvin. Since 0 dimension of k = [M L2 T-2 θ-1], dimensional formula for α = (ML2T- 2ϴ)/ (L) Since Dimensional formula of P =[M L-1T-2], dimensional formula for β = (M LT2)/(ML-1T2 )= M0L2T0

#### The correct order of units for the following will be

Correct! Wrong!

The distance between earth and stars is measured in Light years. The size of nucleus is measured in Fermi. The interatomic distance in a solid is measured in Angstrom.

#### 2Which of the following is not a unit of radiation?

Correct! Wrong!

The tesla (symbol T) is the SI derived unit of magnetic field B (which is also known as "magnetic flux density" and "magnetic induction").

Correct! Wrong!

V = 4/3Πr3

Correct! Wrong!

0.225×100 = 0.8%

#### If the rotational K.E of a body is 1/2 I ω2, then the dimension of I is ____.

Correct! Wrong!

K . E = 1/2Iω2 ∴I = 2×K .E/ω2 = ML2T- 2/T- 2 = M1L2T0 The dimension of I is ML2T- 2/T- 2 = M1L2T0.

#### The dimensions of permittivity of free space is ____.

Correct! Wrong!

According to coulomb's law, F = ε0 = q2 /(F)(r2 ) = A2T2 /(MLT- 2 ) (L2 ) = M- 1L- 3T4A2

#### In physics, one shake equals ____.

Correct! Wrong!

Shake is a unit of time used in microscopic physics. One shake equals 10-8 s.

#### Which among the following - Impulse, force, momentum, work have same dimensions ____ .

Correct! Wrong!

Impulse = force × time = [M L T-2] × T = [M1 L1 T-1] Momentum = mass × velocity M × [L T-1] = [M1 L1 T-1]

#### The significant figure of 5.4 × 0.125 is ____.

Correct! Wrong!

5.4 × 0.125 (Multiply normally) = 0.675 = 0.68 (Rounding off according to significant figures)

#### The length of one rod (l1) = 3.323 cm and the other is (l2) = 3.321 cm. If both rods were measured with one measuring instrument with least count 0.001 cm, then (l1 - l2) is ____

Correct! Wrong!

l1 - l2 = (3.323 ± 0.001) - (3.321 ± 0.001) = (0.002 ± 0.002) cm

#### In the equation y = A sin (ωt - kx), where x is distance and t is time, then the dimensional formula of ω and k are respectively ____.

Correct! Wrong!

angle is dimensionless,
ωt = θ/t = 1/T= T-1
Therefore, ω = [M0L0T-1]
Since kx = θ, k = θ/x = 1/L=L-1
Therefore, k = [M0L-1T0]

#### The length 'l' of a cylinder is given as 1.0 cm. The least count of the instrument used to measure length is ____.

Correct! Wrong!

Significant figures are used to express the order of accuracy of a measurement. If we write l = 1.0 cm, it means that the least count of the instrument with which l is measured is 0.1 cm.

#### The order of age of earth is ____.

Correct! Wrong!

The age of universe is of the order 1017 s.

#### What would be the mass of body that weighs 2 N at a place where g = 9.8 m/s2 ____.

Correct! Wrong!

Here, W = 2 N, g = 9.8 m/s2 ∴m = w/g = 2/9.8 = 0.204 kg

#### 'atto' is equal to 10x. The value of x in 10x is

Correct! Wrong!

Atto- (symbol a) is a prefix in the metric system denoting a factor of 10−18

Class 11th Physics - 2 Units and Measurements MCQs
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