The number of turns in a coil of a galvanomet | vedclass

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(D) The current sensitivity $(I_s)$ of a galvanometer is given by $I_s = \frac{	heta}{I} = \frac{NAB}{k}$,where $N$ is the number of turns,$A$ is the

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Voltage sensitivity remains constant and current sensitivity increases $3$ times.

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(D) The current sensitivity $(I_s)$ of a galvanometer is given by $I_s = \frac{	heta}{I} = \frac{NAB}{k}$,where $N$ is the number of turns,$A$ is the area,$B$ is the magnetic field,and $k$ is the restoring torque constant per unit twist.If $N$ is tripled $(N' = 3N)$,then $I_s' = \frac{(3N)AB}{k} = 3 I_s$. Thus,current sensitivity increases $3$ times.The voltage sensitivity $(V_s)$ is given by $V_s = \frac{	heta}{V} = \frac{	heta}{IR} = \frac{I_s}{R}$.Since the resistance $R$ is proportional to the length of the wire,and the length of the wire is proportional to the number of turns $(R' = 3R)$,the new voltage sensitivity is $V_s' = \frac{3I_s}{3R} = \frac{I_s}{R} = V_s$.Therefore,voltage sensitivity remains constant and current sensitivity increases $3$ times.

The number of turns in a coil of a galvanometer is tripled. Then:

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