Question

What is the voltage across the inductor in the instant just after the switch is closed? Use the following data: V_b = 5.50, V; R = 140.0 Ω; L = 9.28×10^-1 H?

After the switch is closed for a long time, what is the energy stored in the inductor?

Answer 1

Just after the switch is closed inductor works as open circuit and therefore no current flows through it. The voltage of the battery is seen across the inductor.

Voltage across inductor in the instant just after the switch is closed = 5.50 V

After the switch is closed for long time the inductor works as short circuit, current in circuit = 5.5 V / 140 ohm = 0.03928 A

Energy stored in inductor = 1/2 L i^2 = 0.5×0.928×0.03928^2 = 0.0007161224 J or 7.16 × 10^-4 J