• question_answer In a Vernier Calliper, the zero of Vernier scale is slightly left to the zero of main scale when both jaws are closely joined to each other. Total number of divisions on Vernier scale is 80 which is equal to $2.32\text{ }cm.$ 70th division of Vernier is exactly coinciding with 2nd division of main scale when jaws are closely joined to each other. Now diameter of cylinder is measured, it is found that zero of Vernier lies between $6.2\text{ }cm$to $6.23\text{ }cm$on the main scale and 50th division of Vernier exactly coincides with a main scale. Then choose the correct option. A) Vernier callipers has negative zero error of$1.97\text{ }cm$. B) Vernier callipers has positive zero error of$1.97\text{ }cm$. C) Vernier callipers has negative zero error of$0.01\text{ }cm$.    D) Vernier callipers has positive zero error of$0.01\text{ }cm$.

[a] Vernier Callipers has $-ve$zero error. 1 main scale $=0.03$ 1 Vernier scale $=0.029$ Let 'x' be the gap between zero of Vernier scale and Main scale. $x+2\times 0.03=70\times (0.029)$ $x=1.97\,cm$