Question

The resistance of a galvanometer coil is $R$. What is the shunt resistance required to convert it into an ammeter of range $4$ times

• A. $\frac{R}{5}$
• B. $\frac{R}{4}$
• C. $\frac{R}{3}$
• D. $4R$

Answer 1

The correct option is C $\frac{R}{3}$

According to the question,

$\frac{i}{i_g}=1+\frac{G}{S}\Rightarrow \frac{4}{1}=1+\frac{R}{S}\Rightarrow S=\frac{R}{3}$