A moving coil galvanometer A has and resistance . Another meter B has and resistance . All the other quantities are same in both the cases. The current sensitivity of:
B is double as that of A
Step 1: Given
Number of turns of A:
Number of turns of B:
Resistance of A:
Resistance of A:
Step 2: Formula Used:
where I is the reciprocal of current sensitivity, A is the area of the coil, B is the magnetic field, k is the couple per unit twist, and is the angle of deflection.
Step 3: Find the ratio of sensitivity of both galvanometers
Calculate the reciprocal of the current sensitivity of galvanometer A using the formula
Calculate the reciprocal of the current sensitivity of galvanometer B using the formula
Calculate the ratio of current sensitivity by dividing the current sensitivity of A by the current sensitivity of B. Current sensitivity will be the reciprocal of I.
Hence, the current sensitivity of B is 2 times that of A.
Thus, option A is correct.