Question

What is the value of shunt resistance required to convert a galvanometer of resistance $100\Omega$ into an ammeter of range $1A$? Given : Full scale deflection of the galvanometer is 5 mA.

• A. $\frac{5}{9.95}\Omega$
• B. $\frac{9.95}{5}\Omega$
• C. $0.5\Omega$
• D. $0.05\Omega$

Answer 1

The correct option is A $\frac{5}{9.95}\Omega$

Given : $I_g=5mA=0.005A$ $G=100\Omega$ $I=1A$

Let a shunt resistance $R_s$ is connected, as shown in the figure, to convert a galvanometer into an ammeter.

From figure, $V_{AB}=V_{CD}$

$\therefore$ $(I-I_g)R_s=I_{g}G$

OR $(1-0.005)R_s=0.005\times 100$

OR $0.995R_s=0.5$ $⟹R_s=\frac{5}{9.95}\Omega$