Note that, in a galvanometer, the magnetic field is configured such that it is radial and always perpendicular to the magnetic dipole moment of the coil: \[\begin{aligned} \tau_B &= N\mu B sin(90^{\ci...Note that, in a galvanometer, the magnetic field is configured such that it is radial and always perpendicular to the magnetic dipole moment of the coil: \[\begin{aligned} \tau_B &= N\mu B sin(90^{\circ})= NIa^2B\\\end{aligned}\] The deflection, \(\theta\), for a given current will occur when the torque produced by the wire is equal to the torque produced by the spring.
