Q. A galvanometer of resistance, $G,$ is shunted by a resistance $S\ ohm.$ To keep the main current in the circuit unchanged, the resistance to be put in series with the galvanometer is
A) $\frac{G^{2}}{(S + G)}$
B) $\frac{G}{(S + G)}$
C) $\frac{S^{2}}{(S + G)}$
D) $\frac{SG}{(S + G)}$
Explanation
(a) [image:3_image138.emf]
$G = \left( \frac{GS}{G + S} \right) + S''$
$G - \frac{GS}{G + S} = S^{''}\ \therefore S^{''} = \frac{G^{2}}{G + S}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.