Units and Measurements

One main scale division of a vernier caliper is equal to m units. If nth division of main scale coincides with (n + 1)th division of vernier scale, the least count of the vernier caliper is :

1. 1(n + 1)
2. m(n + 1)
3. n(n + 1)
4. mn(n + 1)

The de-Broglie wavelength associated with a particle of mass m and energy E is h/ 2mE. The dimensional formula for Planck's constant is :

1. [ M2 L2 T-2 ]
2. [ ML-1 T-2 ]
3. [ ML2 T-1 ]
4. [ MLT-2 ]

In an expression a 10b :

1. a is order of magnitude for b 5
2. b is order of magnitude for a 5
3. b is order of magnitude for a 5
4. b is order of magnitude for 5 < a 10

Young's modulus is determined by the equation given by Y = 49000 Ml dynecm2 where M is the mass and l is the extension of wire used in the experiment. Now error in Young modulus (Y) is estimated by taking data from M–l plot in graph paper. The smallest scale divisions are 5 g and 0.02 cm along load axis and extension axis respectively. If the value of M and l are 500 g and 2 cm respectively then percentage error of Y is :

1. 2%
2. 0.02%
3. 0.5%
4. 0.2%

The diameter of a sphere is measured using a vernier caliper whose 9 divisions of main scale are equal to 10 divisions of vernier scale. The shortest division on the main scale is equal to 1 mm. The main scale reading is 2 cm and second division of vernier scale coincides with a division on main scale. If mass of the sphere is 8.635 g, the density of the sphere is:

1. 2.2 g/cm3
2. 2.0 g/cm3
3. 1.7 g/cm3
4. 2.5 g/cm3

If o is the permittivity of free space and E is the electric field, then oE2 has the dimensions :

1. [ ML-1 T-2]
2. [ ML2 T-2]
3. [ M0L-2TA]
4. [ M-1 L-3 T4 A2]

There are 100 divisions on the circular scale of a screw gauge of pitch 1 mm. With no measuring quantity in between the jaws, the zero of the circular scale lies 5 divisions below the reference line. The diameter of a wire is then measured using this screw gauge. It is found that 4 linear scale divisions are clearly visible while 60 divisions on circular scale coincide with the reference line. The diameter of the wire is :

1. 4.65 mm
2. 4.60 mm
3. 4.55 mm
4. 3.35 mm

Least count of a vernier caliper is 120 N cm. The value of one division on the main scale is 1 mm. Then the number of divisions of main scale that coincide with N divisions of vernier scale is :

1. ( 2N - 12N )
2. ( 2N - 120N )
3. (2N - 1)
4. ( 2N - 12 )

To find the spring constant (k) of a spring experimentally, a student commits 2\% positive error in the measurement of time and 1\% negative error in measurement of mass. The percentage error in determining value of k is :

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

While measuring diameter of wire using screw gauge the following readings were noted. Main scale reading is 1 mm and circular scale reading is equal to 42 divisions. Pitch of screw gauge is 1 mm and it has 100 divisions on circular scale. The diameter of the wire is x50 mm. The value of x is :

1. 42
2. 71
3. 21
4. 142