
Physics Class XI (JEE/Neet) Topic : Unit and measurements
QuizĀ by Swati Pawar
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3.1 light year distance is equal toĀ
(a) 9.46 1010 ā km (b) 9.46 1012 ā kmĀ
(c) 9.46 109Ā ā km (d) 9.46 1015 ā km
4.Ā Parallactic second is equal toĀ
(a) 9.4605 1015 ā m (b) 3.07 1016 ā mĀ
(c) 1.496 1011 ā m (d) 3 108Ā ā m
5.Ā A new unit of length is chosen such that the speed of light in vacuum is unity. What is the distance between the sun and the earth in terms of the new unit, if light takes 8 min and 20 s to cover this distance?Ā
(a) 300 (b) 400 (c) 500 (d) 600Ā
6.Ā A student measures the thickness of a human hair by looking at it through a microscope of magnification 100. He makes 20 observations and finds that the average width of the hair is 3.5 mm. What is the estimate on the thickness of the hair?Ā
(a) 0.0035 mm (b) 0.035 mmĀ
(c) 0.01 m (d) 0.7 m
7.Ā The dimensions of impulse are equal to that of
(a) force (b) linear momentum (c) pressure (d) angular momentumĀ
8.Ā The dimensional formula for molar thermal capacity is same as that ofĀ
(a) gas constant (b) specific heatĀ
(c) Boltzmannās constant (d) Stefanās constantĀ
9.Ā Ā In measuring electric energy, 1kWh is equal to
Ā (a) 3.6 10 J 4Ā ā
(b) 3.6 10 J 6Ā ā Ā
(c) 7.3 10 J 6Ā ā
(d) None of theseĀ
10.Ā Out of the following four dimensional quantities, which one qualifies to be called a dimensional constant? (a) Acceleration due to gravityĀ
(b) Surface tension of waterĀ
(c) Weight of a standard kilogram massĀ
(d) The velocity of light in vacuumĀ
11.Ā The square root of the product of inductance and capacitance has the dimensions ofĀ
(a) lengthĀ
(b) timeĀ
(c) massĀ
(d) no dimensionĀ
12.Ā Ā With usual notation, the following equation, said to give the distance covered in the nth second, i.e. s u anĀ
n = +( ) 2 1 ā2isĀ
(a) numerically correct onlyĀ
(b) dimensionally correct onlyĀ
(c) both dimensionally and numerically onlyĀ
(d) neither numerically nor dimensionally correct
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33.Ā [ML T A ] 2 3 1 ā ā is the dimensional formula forĀ
(a) capacitance (b) resistanceĀ
(c) resistivity (d) potential differenceĀ
34.Ā The dimensional formula [ML T ] 0 3āis more closely associated withĀ
(a) powerĀ
(b) energyĀ
(c) intensityĀ
(d) velocity gradient
35.Ā Assuming that the mass mof the largest stone that can be moved by a flowing river depends upon the velocity v of the water, its density Ļand the acceleration due to gravity g. Then, mis directly proportional toĀ
(a) v3(b) v4Ā
(c) v5(d) v6Ā
36.Ā The units of length, velocity and force are doubled. Which of the following is the correct change in the other units?Ā
(a) Unit of time is doubledĀ
(b) Unit of mass is doubledĀ
(c) Unit of momentum is doubledĀ
(d) Unit of energy is doubled
37.Ā The dimensional representation of specific resistance in terms of charge Q isĀ
(a) [ML T Q ] 3 1 2 ā ā (b) [ML T Q ] 2 2 2 āĀ
(c) [MLT Q ] ā ā 2 1 (d) [ML T Q ] 2 2 1 ā āĀ
38.Ā IfC and R denote capacity and resistance, the dimensions of CR areĀ
(a) [M L T] 0 0Ā
(b) [ML T] 0Ā
(c) [M L T ] 0 0 2Ā
39.Ā Multiply 107.88 by 0.610 and express the result with correct number of significant figures.Ā
(a) 65.8068 (b) 64.807 (c) 65.81 (d) 65.8Ā
40.Ā The unit of permittivity of free space, ε0is (a) coulomb/newton-metreĀ
(b) newton-metre 2/coulomb2Ā
(c) coulomb2/newton-metre 2Ā
(d) coulomb2/(newton-metre)Ā 2
41.Ā Ā Three measurements are made as 18.425 cm, 7.21 cm and 5.0 cm. The addition should be written asĀ
(a) 30.635 cm (b) 30.64 cm (c) 30.63 cm (d) 30.6 cm
42.Ā The radius of a thin wire is 0.16 mm. The area of cross-section of the wire in mm2 with correct number of significant figures isĀ
(a) 0.08 (b) 0.080Ā
(c) 0.0804 (d) 0.080384Ā
43 .Ā The mass of a box is 2.3 kg. Two gold pieces of masses 20.15 g and 20.17 g are added to the box. The total mass of the box to correct significant figures isĀ
(a) 2.3 kg (b) 2.34 kgĀ
(c) 2.3432 kg (d) 2.31 kgĀ
44 .Ā Ā The length of a rod is (11.05 0.2) cm ± . What is the length of the two rods?Ā
(a) (22.1 0.05) cm ±Ā
(b) (22.1 0.1) cm ±Ā
(c) (22.10 0.05) cm ±Ā
(d) (22.10 0.2) cm ±Ā
45.Ā Ā Pressure gradient has the same dimensions as that of
(a) velocity gradient
(b) potential gradient
(c) energy gradient
(d) None of theseĀ
46 .Ā Ā Which one of the following have same dimensions?
(a) Torque and forceĀ
(b) Potential energy and forceĀ
(c) Torque and potential energyĀ
(d) Planckās constant and linear momentumĀ
47.Ā 58. The significant figures of the number 6.0023 is
(a) 2
(b) 5Ā
(c) 4
(d) 1Ā
48.Ā In which of the following numerical values, all zeros are significant?Ā
(a) 0.2020
(b) 20.2Ā
(c) 2020
(d) None of theseĀ
49.Ā Ā If the error in measuring diameter of a circle is 4%, the error in measuring radius of the circle would be
(a) 2%
(b) 8%Ā
(c) 4%
(d) 1%Ā
50.Ā A cuboid has volumeV l l l = ā ā 2 3 , where l is the length of one side. If the relative percentage error in the measurement of l is 1%, then the relative percentage error in measurement ofV isĀ
(a) 18%
(b) 6%Ā
(c) 3%
(d) 1%Ā