Write the equation for the maximum torque acting on a current-carrying loop in a galvanometer.

(N/A) The torque $\tau$ acting on a current-carrying coil of area $A$ with $N$ turns,placed in a magnetic field $B$,is given by the formula: $\tau = N I A B \sin(\theta)$,where $\theta$ is the angle between the normal to the coil and the magnetic field.
For a radial magnetic field in a galvanometer,the plane of the coil is always parallel to the magnetic field lines. This means the angle between the normal to the coil and the magnetic field is always $90^\circ$.
Since $\sin(90^\circ) = 1$,the maximum torque is given by: $\tau_{max} = N I A B$.