Least count of a vernier calliper is 0.01cm. When the two jaws of the instrument touch each other the 5thdivision of the vernier scale coincides with a main scale division and the zero of the vernier scale lies to the left of the zero of the main scale. Furthermore while measuring the diameter of a sphere, the zero mark of the vernier scale lies between 2.4cm and 2.5cm and the 6thVernier division coincides with a main scale division. Calculate the diameter of the sphere.(1) 2.51cm (2) 5.12cm (3) 2.51mm (4) 5.12mm.

Answer: (1)

Given parameters

Least count = 0.01cm

Main scale reading (MSR) = 2.4cm

Vernier scale divisions (VSD) = 6.

The instruments have a negative error.

e = (-5 × 0.01)

e = -0.05cm

So the total reading of the diameter of the sphere

R = MSR+(VSD×LC)+ zero error

R = 2.4 + (6 × 0.01) + (0.05)

R = 2.51cm