For an LCR circuit, the power transferred from the driving source to the driven oscillator is `P = I^(2) Z cos phi`.

Options

A. the power factor `cos phi ge 0, P ge 0`
B. the driving force can give no energy to the oscillator(P = 0) in some cases.
C. the driving force cannot syphon out `(P lt 0)` the energy out of oscillator.
D. all of these.

Answer

D

Explanation

Here, `P = I^(2)Z cos phi`
(a) If power factor `cos phi ge 0 rArr P ge0`
(b) For wattless component the driving force shall give no energy to the oscillator, so, at `phi = 90^(@), P = 0`.
(c ) The driving force cannot syphon out the energy out of oscillator. i.e. P cannot be negative.
Hence all options are correct.