Question

A galvanometer of $25\Omega$ internal resistance is joined with a shunt of $0.5\Omega$. If the combination is used as an ammeter, the ratio of the currents flowing through the galvanometer and the shunt is

• A. $50:1$
• B. $1:50$
• C. $1:100$
• D. $100:1$

Answer 1

Answer: (B)

$1:50$

In case of ammeter, the shunt and galvanometer are connected in parallel.

According to ohms law: $I=\frac{V}{R}$

V across the shunt and galvanometer is same as both are in parallel.

Current flowing in the galvanometer $=\frac{V}{50R}$

Current flowing in the shunt $=\frac{V}{0.5R}$

So, the ratio of currents flowing through the galvanometer and the shunt is $=\frac{\frac{V}{25R}}{\frac{V}{0.5R}}=\frac{1}{50}$