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A series LCR circuit is connected to an ac voltage source. When L is removed from the circuit, the phase difference between current and voltage is π/3. If instead C is removed from the circuit, the phase difference is again π/3 between current and voltage. The power factor of the circuit is:

1. 0.5
2. 1.0
3. zero
4. 1

Correct answer: 0.5

Solution

When L is removed, the circuit becomes capacitive, and the phase difference is π/3. When C is removed, the circuit becomes inductive, and the phase difference is again π/3. This implies that the inductive reactance and capacitive reactance are equal in magnitude, leading to a power factor of cos(π/3) = 0.5.

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