A moving coil galvanometer has a coil of effective area A and number of turns N. The magnetic field B is radial. If a current I is passed through the coil, the torque acting on the coil is

$NABI$

The correct answer is Option (3) → $NABI$

The torque on a moving coil galvanometer is given by:

$\tau = N \cdot I \cdot A \cdot B$

Where:

• $N$ = number of turns
• $I$ = current through the coil
• $A$ = area of the coil
• $B$ = magnetic field (radial)

∴ Torque acting on the coil = N I A B