Question

The deflection of a moving coil galvanometer reduces to half, on shunting it with a resistance of $60\Omega$. The resistance of galvanometer is

• A. $30\Omega$
• B. $120\Omega$
• C. $60\Omega$
• D. $15\Omega$

Answer 1

The correct option is C $60\Omega$

Consider the circuit shown in figure. Let $I$ is the initial current through circuit and $R$ is the resistance of galvanometer.
Since, shunt and galvanometer are in parallel, voltage across them is same.
Hence,
$\frac{I}{2}R=\frac{I}{2}60$ ........................$($since, $V=IR)$
$\Rightarrow R=60\Omega$