Question

The vernier of a circular scale is divided into 50 divisions which coincides with 49 main scale division .Each main scale division is 0.5${}^o$.The least count of the instrument is

• A. 0.6'
• B. 1'
• C. 6'
• D. 30'

Answer 1

Answer: (A)

0.6'

$50C\cdot S\cdot D=49M\cdot S\cdot D$

$\begin{array}{cc}1VSD& =\frac{49}{50}mSD\\ \text{IVSD}& =\frac{49}{50}\times {0.5}^{\circ }\\ & ={0.49}^{\circ }\end{array}$

$C\cdot S\cdot D\left(Circularscaledivison\right)=VSD$

$\begin{array}{cc}L\cdot C& =1MSD-1VSD\\ & ={0.01}^0\\ & =0.01\times 60{}^{\prime }\\ & =0.6{}^{\prime }\end{array}$