Question

A galvanometer has a resistance G and a current $i_g$ flowing in it produces full scale deflection. $S_1$ is the value of shunt, which converts it into an ammeter of range 0-I and $S_2$ is the value of shunt for the range 0-2I the ratio $S_1$ / $S_2$ is

• A. $\frac{S_1}{S_2}=\left[\frac{2I-ig}{I-ig}\right]$
• B. $\frac{S_1}{S_2}=\frac{1}{2}\left[\left(\frac{I-i_g}{2I-i_g}\right)\right]$
• C. 2
• D. 1

Answer 1

Answer: (A)

$\frac{S_1}{S_2}=\left[\frac{2I-ig}{I-ig}\right]$

$S=\frac{I_{g}G}{(I-I_g)}$ (using standard relationship)

$S_1=\frac{i_{g}G}{(I-i_g)}$

$S_2=\frac{i_{g}G}{(2I-i_g)}$

$\frac{S_1}{S_2}=\frac{2I-i_g}{I-i_g}$