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Power factor of pure resistive load:
AVariable
B0
C0.5
D1.0 (unity — V and I in phase)
Answer & Solution
Correct answer: D. 1.0 (unity — V and I in phase)
Pure R: V and I in phase, cos φ = cos 0° = 1. Maximum real power for given V_rms × I_rms. Resistive loads (heaters, incandescent bulbs): pf ≈ 1. Inductive (motors, transformers): pf lagging (0.7-0.9). Capacitive: pf leading.
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