CONCEPT:Deflecting torque of the PMMC meter is given as,Td = NBAI = GI Where,Td = deflecting torque in N-mB = flux DENSITY in air gap, Wb/m2N = NUMBER of turns of the coilsA = effective area of the coil in m2I= current passing through the meter, amperesG = constant = NBAThe spring control provides a restoring (controlling) torque given as,Tc = Kθ (Nm)K = spring constant (Nm/degree)θ = angle of deflection in degreeFor final steady-state deflection conditionTd = Tc Td = Kθ --- equation (1)Calculation:Given dataSpring constant K= 0.2 × 10-6 Nm/degreeDeflecting torque Td = 24 × 10-6 NmFrom equation(1)Td = Kθ24 × 10-6 = 0.2 × 10-6 × θ θ = 120°