Aseries lr circuit contains an emf source of 14 v having no internal resistance, a resistor, a 34 h inductor having no appreciable resistance, and a switch. if the em across the inductor is 80% of its maximum value 4.0 s after the switch is closed, what is the resistance of the resistor? a) 1.9 ω b) 1.50 ω c) 14 ω d) 5.0 ω

(a) 1.9 ohm

Explanation:

We have given voltage across LR circuit

Inductance L = 34 Henry

Time t = 4 sec

It is given that emf across the inductor is 80% of maximum value in 4 sec

The voltage across RL circuit is given by

, here is time constant which is for RL circuit

Now according to question

We know that

R = 1.9 ohm

So option (a) is correct