Question

When shunt of $4 \, \Omega $ is attached to a galvanometer, the deflection in the galvanometer is reduced to $\frac{1}{5}th$ . If an additional shunt of $2 \, \Omega $ is also connected. The deflection of galvanometer will be reduced to

• A. $\frac{1}{10}th$ of initial
• B. $\frac{1}{13}\text{th}$ of initial
• C. remains the same
• D. none of these

Answer 1

Answer: (B)

Intial condition

When shunt of $4\Omega $ is used, $\frac{i}{5}\times G=\frac{4}{5}i\times 4$

$\Rightarrow G=16\Omega $
When additional shunt of $2\Omega $ is attached,
$i^{'}\times 16=\left(i - i^{'}\right)\frac{4}{3}$
$12i^{'}=i-i^{'}$
$\Rightarrow i'=\frac{1}{13}$

It will reduce to $\frac{1}{13}$ of the initial value.