An LCR series circuit with a resistance of 100 ohm is connected to an ac source of 100 V (r.m.s.) and angular frequency 300 rad/s. When only the capacitor is removed, the current lags behind the voltage by . When only the inductor is removed the current leads the voltage by . The average power dissipated is
tanϕ=XLR=XCR⇒ tan60∘=XLR=XCR
⇒ XL=Xc=√3R
i.e. Z =√R2+(XL−Xc)2=R
So average power P=V2R=100× 100100=100 W