Question

N divisions on the main scale of a vernier calipers coin sides with (N + 1) divisions on the vernier scale. If each division on the main scale is of a units, the least of count of instrument is..................

(A) {a / (N + 1)}

(B) {a / (N – 1)}

(C) {(N + 1) / a}

(D) {(N – 1) / a}

Answer 1

The correct option is (A) {a / (N + 1)}.

Explanation:

(N + 1) division on the vernier scale = N division on main scale

∴ 1 division on vernier scale = {N / (N + 1)} division on main scale Each division on main scale is of "a" units hence

∴ 1 division on vernier scale {N / (N + 1)} a units = a1 (say)

∴ LC = 1 main scale division – 1 vernier scale division

= a – a1

= a – {N / (N + 1)} a

LC = {a / (N + 1)}