Given below are two statement:
Statement-wir if the number of turns in the coil of a moving coil galvanometer is doubled then the current sensitivity becomes double.
Statement-II : Increasing current sensitivity of a moving coil galvanometer by only increasing the number of turns in the coil will also increase its voltage sensitivity in the same ratio:
In the light of the above statement, choose the correct answer from the options given below:
Select the correct option:
A
Statement I is false but Statement II is true
B
Both Statement I and Statement II are true
C
Both Statement I and Statement II are false
D
Statement I is true but Statement II is false
✓ Correct! Well done.
✗ Incorrect. Try again or view the solution.
Solution
Sol. For a moving coil galvanometer
$$
\begin{aligned}
& \operatorname{BiNA}=k \theta \\
& \theta=\left(\frac{B N A}{k}\right) i ; \text { Current sensitive }=\frac{B N A}{k}
\end{aligned}
$$
So, if N is doubled then current sensitivity is doubled.
Voltage sensitivity $B \frac{V}{R} N A=k \theta$
$\mathrm{V}=\frac{\mathrm{BNA}}{\mathrm{Rk}} \theta$, as N is doubled R is also doubled.
So, no change in voltage sensitivity.
Hence, option (4) is right.
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