Question

The least count of a vernier callipers is 0.01 cm. if the jaws of the vernier callipers are joined and the zero of both coincide, then the distance of the seven marks of the two scales will be

• A. 7 x 0.01 mm
• B. 7 -0.01 cm
• C. 7 x 0.01 cm
• D. 7/0.01 cm

Answer 1

The correct option is C 7 x 0.01 cm

10 divisions in the vernier scale are equal to 9 divisions on the vernier scale. Thus each division on the vernier scale is equal to 0.9 divisions on the vernier scale
since zero'es of both the scales coincide, the seventh division on the vernier scale is at a distance of 0.9 $\times$ 7 = 6.3 mm from the zero of the vernier. The seventh division on the main scale will be at a distance of 7 mm from the zero of the main scale. Thus, distance between them will be 7 - 6.3 = 0.7 mm = 7 $\times$ 0.01 cm