Question

A moving-coil galvanometer has its coil of $24$ turns and $12\Omega$ resistance. By how much the number of turns should be increased so that the current sensitivity of the galvanometer increases by $25$%? If, in doing so, the resistance of the coil increases to $20\Omega$, what will be the effect on the voltage-sensitivity of the galvanometer?

Answer 1

Turns must be increased from $24$ to $30$; voltage - sensitivity will fall by $25$%.