a. The inductance of an air core coil is 0.08H, and the effective resistance is 4 ohms when a 60V, 50Hz source is connected across the coil. Find the current passing through the coil and the reading of a watt meter across the coil.
b. If a brass core is inserted in the coil the effective resistance increases to 7 ohms and the wattmeter reads 30 W. Find the current passing through the coil and the inductance of the coil.
c. If a solid iron core is inserted in the coil, the resistance of the coil increases to 10 ohms and the current decreases to 1.7 A. Find the wattmeter reading and the inductance of the coil.