Question

A galvanometer has a resistance of $100\Omega$ . A potential difference of $100mV$ between its terminals gives a full scale deflection. The shunt resistance required to convert it into an ammeter reading upto $5A$ is

• A. $0.01\Omega$
• B. $0.02\Omega$
• C. $0.03\Omega$
• D. $0.04\Omega$

Answer 1

Answer: (B)

The current required for full-scale deflection is $\begin{array}{l}{i}_g=\frac{PD\text{ across galvanometer }}{\text{ resistance of galvanometer }}\\ i_g=\frac{100\times 10^{-3}}{100\Omega }=10^{-3}A\end{array}$ The shunt resistance required is $S=\left(\frac{i_g}{i-i_g}\right)G=\left(\frac{10^{-3}}{5-10^{-3}}\right)\times 100=0.02\Omega$