Assertion : The power in ac circuit is minimum if the circuit has only a resistor.
Reason : Power of a circuit is independent of the phase angle.

Options

A. If both assertion ans reason are true ans reaason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion istrue but reason is false.
D. If both assertion and reason are false.

Answer

D

Explanation

Power in a series ac circuit consisting of L,C and R is given by
`P = I_("rms")V_("rms")cos phi` where `phi = tan^(-1)((|X_(L)-X_(C)|)/(R ))`
For a purely resistive circuit `X_(L) = 0` and `X_(C) = 0`
Therefore, `tan phi = 0` or `phi = 0` and thereby `cos phi = 1` and P = IV.
The power is maximum as `cos phi` is maximum. Power depends on the phase angle through the power factor `cos phi`.