Answer: Power factor is the cosine of the phase angle between voltage and current. If we look at the other definition of power factor it is the ratio of true power to the apparent power. Here you can see exactly that apparent power is always greater than true power. True power can never exceed apparent power. True power may be equal to apparent power but cannot exceed. So that is why power factor can not more than unity.
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MCQ or objective
The defination of power factor is the cosine angle between voltage and current but maximum cosine value is 1 and minimum is -1. So power factor above 1 is impossible.
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