A coil of inductance 20 H and resistance 5 Ω is connected to a DC voltage source. When the voltage is applied, the initial rate of increase of current is 4 A/s. What is (a) the value of the applied...

A coil of inductance 20 H and resistance 5 Ω is connected to a DC voltage source. When the voltage is applied, the initial rate of increase of current is 4 A/s. What is (a) the value of the applied voltage, (b) the rate of growth of the current when the circuit current is 5 A?