Question

Consider an RL series circuit having resistance R = 3 Ω, inductance L = 3 H and is excited by 6V. The current after a long time after closing of switch is ____________

(a) 1 A

(b) 2 A

(c) 0 A

(d) Infinity

Answer 1

The correct choice is (b) 2 A

To elaborate: At t = ∞ the circuit has effectively two 6Ω resistances in parallel.

So, REQ = \(\frac{6 X 6}{6 + 6}\)

= \(\frac{36}{12}\) = 3 Ω

Given voltage = 6 V

So, current = 2 A.