In an `L-C-R` ereis circuit `R=150Omega, L=0.0750 H` and `C=0.0180muF` . The source has voltage amplitude `V=150V` and a frequencey equal to the resonacne frequency of the circuit.
(a) What is the power factor ?
(b) What is the average power delivered by the source?
(c) The capacitor is replaced by one with `C=0.0360muF` and the source frequency is adjusted to the new resonance value. Then, what is the average power delivered by the source?

Explanation

(a) At resonance frequency,
`X_L=X_C,Z=R` and power factor `cosphi=R/Z=1.0`
(b) `P=V_(rms)^2/R=((150//sqrt(2))^(2))/(150)=75W`
(c) Again `P=V_("rms")^2/R=75W`.