A bulb of resistance 10 Ω, connected to an inductor of inductance L, is in series with a source marked 100 V, 50 Hz. If the phase angle between the voltage and current is π/4 radian. The value of L will be:

Concept:

LR Circuit:

• An LR Circuit is an electrical circuit consisting of an inductor (L), resistor (R) it can be connected either parallel or series.
• Let the applied voltage be V = V₀Sinωt, then the instantaneous current leads the voltage by an angle ϕ then
• The instantaneous voltage and current  is given by

The phase angle is given by:-

Where X_L = Inductive reactance, R= Resistance

Calculation:

Calculate the value of L

Now, 

f = 50 Hz, R = 10 Ω

= 0.032 H