Question

The circuit shows a RLC circuit energized by a dc source of emf E. At t =0 the source is switched on

• A. at t =0; current through the source is $\frac{2E}{3R}$
• B. at $t=\infty$ ; current through the source is $\frac{2E}{3R}$
• C. at t =0; current through the source is $\frac{2E}{R}$
• D. at t =0; current through the source is $\frac{E}{2R}$

Answer 1

Answer: (A), (B)

The correct options are
A at t =0; current through the source is $\frac{2E}{3R}$
B at $t=\infty$ ; current through the source is $\frac{2E}{3R}$

at t =0; replace capacitors with short ckt and inductors open ckt and at $t=\infty ,$ replace capacitor with open ckt and inductor with short ckt.
By doing that the circuit will be simplified which will result in a current of $\frac{2E}{3R}$ at t = 0 and at t = $\infty$ both.