A galvanometer is said to be sensitive if it gives a large deflection for a small current.
The current sensitivity of a meter is the deflection of the meter per unit current, i.e., α/I. It is given by
The sensitiveness can be increased by increasing N, A and B and decreasing the value of ‘k’. But N and A cannot be increased much because this will increase the length and consequently the resistance of the coil. In that case, the galvanometer will not respond to weak electric currents. B can be increased by using a strong magnet. ‘k’ can be decreased by using phosphor-bronze for suspension. ‘k’ can be further reduced by using quartz suspension fibre.
