Question

Identify the expression for average power.

(a) Pav=\(\frac {V_o I_o}{2}\)sinΦ

(b) Pav=\(\frac {V_o I_o}{2}\)cosΦ

(c) Pav=\(\frac {V_o I_o}{4}\)cos⁡Φ

(d) Pav=2VoIosin⁡Φ

I had been asked this question in an international level competition.

Origin of the question is Power in AC Circuit : The Power Factor in section Alternating Current of Physics – Class 12

Answer 1

Correct choice is (b) Pav=\(\frac {V_o I_o}{2}\)cosΦ

The explanation is: Average power can be defined as the power averaged over one full cycle of alternating current. It is also known as true power. The expression for average power is given by:

Pav=VrmsIrmscos⁡Φ=\(\frac {V_o I_o}{2}\)cosΦ