Practice portal › Alternating Current › Power in AC Circuits

In an electrical circuit, R, L, C and an ac voltage source are all connected in series. When L is removed from the circuit, the phase difference between the voltage and the current in the circuit is π/3. Instead, if C is removed from the circuit, the phase difference is again π/3. The power factor of the circuit is

Asked in NEET 2013 · Power factor

Answer: (3) 1

Step-by-step solution

Removing L leaves RC with tan π/3=(X_C)/R; removing C leaves RL with

tan π/3=(X_L)/R.

Equal tangents mean X_L=X_C.

With both present those reactances cancel, the circuit is at resonance, Z=R, and

cos φ=R/Z=1.

Why the other options are wrong

More Power in AC Circuits questionsAll Power in AC Circuits questions →

Reading this solution needs no sign-in. You only sign in to practise against the clock and keep your progress.

Practise this with a timer