A moving-coil voltmeter has a resistance of 2002 and full-scale deflection of 120 is reached when a potential difference of 100 mV is applied across its terminals. The moving coil has the effective dimensions of 3.1 cm x 2.6 cm and is wound with 120 turns. The flux density in the gap is 0.15 Wb/m2. Determine the control constant of the spring and suitable diameter of copper wire for coil winding if 55% of total instrument resistance is due to coil winding. p for copper = 1.73 10-6 cm