A galvanometer has a sensitivity of 60 division/ampere. When a shunt is used its sentivity becomes 10 divisions/ampere. What is the value of shunt used if the resistance of the galvanometer is `20Omega`?

Options

A. `4 Omega`
B. `5 Omega`
C. `20 Omega`
D. `8 Omega`

Answer

A

Explanation

The deflection `theta` is proportional to current (I). In this case,`I_g/I=10/60=1/6 but I_g/I=s/(s+G)therefore 1/6=s/(s+20)therefore 6s=s+20 therefore 5s=20 therefore s=4Omega`.