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

1. 1/2
2. 1/√2
3. 1
4. √3/2

Correct answer: 1/√2

Solution

When L is removed, the circuit becomes capacitive, and when C is removed, it becomes inductive. In both cases, the phase difference is π/3, indicating that the circuit is operating at a power factor of cos(π/3) = 1/2.

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