Question

A moving coil galvanometer A has 200 turns and resistance 100 . Another meter B has 100 turns and resistance 40 . All the other quantities are same in both the cases. The current sensistivity of

• A. B is double as that of A
• B. A is 2.5 times of B
• C. A is 5 times of B
• D. B is 5 times of A.

Answer 1

The correct option is A B is double as that of A

for moving coil galvanometer

$I=\left(\frac{C}{NBA}\right)\varphi$

$\left(\frac{\varphi }{I}\right)=\left(\frac{NBA}{C}\right)$

current sensitivity $\left(\frac{\varphi }{I}\right)=\left(\frac{NBA}{C}\right)$

$\frac{currentsensitivityofA}{currentsensitivityofB}=\frac{N_1}{N_2}$

=$\frac{200}{100}$

=2:1