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In a moving coil galvanometer, the principle of operation relies on balancing two torques:1. The magnetic torque (τmagnetic) exerted on the coil due to the current flowing through it in a magnetic field. For a coil in a radial magnetic field, this is given by τmagnetic = N I A B, where N is the number of turns, I is the current, A is the area of the coil, and B is the magnetic field strength.2. The restoring torque (τspring) provided by the suspension spring, which opposes the deflection. This is given by τspring = kΘ, where k is the spring constant and Θ is the deflection angle.At equilibrium, these two torques balance each other: τmagnetic = τspring.Therefore, N I A B = kΘ, which can be rearranged as KΘ = BIAN.