A galvanometer coil has a resistance of `10 Omega` and the meter shows full scale deflection for a current of 1 mA. The shunt resistance required to convert the galvanometer into an ammeter of range 0 - 100 m A is about

Options

A. `10 Omega`
B. `1 Omega`
C. `0.1 Omega`
D. `0.01 Omega`

Answer

C

Explanation

As `R_G = 10 Omega, I_g = 1 mA and I = 100 mA`
`:.` Shunt resistance `r_s = (R_G cdot I_g)/(I - I_g) = (10 Omega xx 1 mA)/((100 mA - 1 mA)) = 10/99 Omega = 0.1 Omega` (appx.)