Question

Sensitivity of a moving coil galvanometer can be increased by:
A. Decreasing the number of turn of coil
B. Increasing the number of turn of coil
C. Decreasing the area of coil
D. By using a weak magnet

Answer 1

Hint: We can solve this question by finding out the proportionality of the given quantities with the sensitivity of galvanometer using the formula that relates sensitivity to the given quantities. Sensitivity of a galvanometer is given by the formula as follows,
$k=I\theta =CNBA$
where N is the number of turns, A is the area of the coil, B is the magnetic field of the magnet and C is the torque per twist in the galvanometer.

Complete step-by-step answer:
Sensitivity of a moving coil galvanometer is defined as the current I in microampere required to consume 1 milli deflection. From the formula we know that the sensitivity can be given by the formula,
 $k=I\theta =CNBA$
Thus we see that the sensitivity of the galvanometer is directly proportional to Number of turns in the coil that is N and it is also directly proportional to Area of the coil that is A. So, sensitivity of the galvanometer can be increased either by increasing the number of turns (N), using strong magnets or increasing the area of the coil (A).
So, the correct answer is that the sensitivity of a moving coil galvanometer can be increased by increasing the number of turns of the coil.

So, the correct answer is “Option B”.

Note: A galvanometer can be defined as an electromechanical instrument which is used for detecting an electric current in a given electric circuit. A galvanometer works by producing a rotary deflection, in response to electric current flowing through a coil kept in a constant magnetic field.