Question

A vernier calliper has each main scale division equal to 1 mm. 20 vernier scale divisions are equal to 16 main scale divisions. The least count of this vernier calliper is
(1)0.1 mm
(2)0.2 mm
(3)0.02 mm
(4)0.04 mm​

Answer 1

answer : option (2) 0.2 mm

explanation : we know,

least count of Vernier calliper = 1 main scale division - 1 vernier scale division

it is given that,

20 vernier scale division = 16 main scale division

so, 1 Vernier scale division = 16/20 main scale division

so, least count of this Vernier calliper = (1 - 16/20) main scale division

= 4/20 main scale division

= 1/5 main scale division

also given , 1 main scale division = 1mm

so, 1/5 main scale division = 1/5 = 0.2 mm

hence, least count of this Vernier calliper = 0.2 mm

hence, option (2) is correct

Answer 2

A vernier callipers has two scales:  

1. The main scale

2.The vernier scale.

Least count = 1 main scale division - 1 vernier scale division

16 Main scale = 20 Vernier scale

1 Vernier scale = 16/20 Main scale

Least count = 1 - 16/20  Main scale

main scale =  1mm

Lease count = 1 - 16/20 mm

= 4/20 mm

= 0.2 mm

Option (2) - 0.2 mm is correct