Moving Charges and Magnetism - Result Question 77
79. 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 [2011M]
(a) $\frac{S^{2}}{(S+G)}$
(b) $\frac{SG}{(S+G)}$
(c) $\frac{G^{2}}{(S+G)}$
(d) $\frac{G}{(S+G)}$
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Answer:
Correct Answer: 79. (c)
Solution:
- (c) To keep the main current in the circuit unchanged, the resistance of the galvanometer should be equal to the net resistance.
$\therefore G=(\frac{GS}{G+S})+S^{\prime}$
$\Rightarrow G-\frac{GS}{G+S}=S^{\prime}$
