What do you mean by current sensitivity of a moving coil galvanometer? On what factors does it depend?

Explanation

Merits of Moving Coil galvanometer :
1. A very small electric current can be detected in the circuit as it is very sensitive.
2. Linear scale can be used because deflection of coil is directly proportional to the current.
3. It is a dead beat type galvanometer.
4. It can be made ballistic by using a non-conducting frame instead of a metallic frame.
Demerits of Moving Coil Galvanometer :
1. It is a bulky device and hence difficult to handle
2. It has to be calibrated before use.
(b) Current Sensitivity : Current senstivity of a galvanometer is defined as the deflection produced in the galvanometer per unit current flowing through it.
`therefore` Current sensitivity, `I_(s) = (alpha)/(I) = (nBA)/(k) " " (because I=(kalpha)/(nAB))`
The unit of current sensitivity is rad `A^(-1)` or div. `A^(-1)`.
Thus, the current sensitivity of a moving coil galvanometer can be increased by
(i) increasing the magnetic field (B).
(ii) increasing the number of turns (n) of the coil.
(iii) increasing the area of coil
(iv) decreasing the restoring torque per unit twist (k).