Question

The one division of main scale of Vernier callipers reads 1mm and 10 divisions of Vernier scale is equal to the 9 division on main scale. When the two jaws of the instrument touch each other, the zero of the Vernier lies to the right of zero of the main scale and its fourth division coincides with a main scale division. When a spherical bob is tightly placed between the two jaws, the zero of the Vernier scale lies in between 4.1 cm and 4.2 cm and 6th Vernier division coincides with a main scale division. The diameter of the bob will be ___ × 10-2 cm.

Answer 1

The correct answer is 412
1 MSD = 1 mm
10 VSD = 9 MSD
LC $=\frac{1}{10} mm$
$0+4(\frac{1}{10}) mm=0.4 mm$
Reading $=41+6(\frac{1}{10})$
= 41 + 0.6
= 41.6 mm
True reading = 41.2 mm
= 412 × 10–2 cm
Therefore , diameter of the bob will be 412 × 10–2 cm.