Question

2N division on main scale of a vernier calliper coincide with $ 15(\mu -1)\lambda $ division of the vernier scale if each division on main scale is of b units, least count of instrument is

• A. $ 25(\mu -1)\lambda $
• B. $ \frac{25\lambda }{(\mu -1)} $
• C. $ {{v}_{P}}=0,\,\,{{v}_{Q}}=v $
• D. $ {{v}_{P}}=v,\,\,{{v}_{Q}}=0 $

Answer 1

Answer: (B)

According to the question $ (2N+1)VSD=2N\,\,MSD $ $ \therefore $ $ 1VSD=\frac{2N}{2N+1}MSD $ Least count = (1MSD - 1VSD) (value of MSD) ; $ 1VSD=\frac{2N}{2N+1}MSD $ $ =\left( \frac{2N+1-2N}{2N+1} \right)b=\frac{1}{(2N+1)} $