When an alternating voltage E = E_o sin $$\omega$$t is applied to a circuit, a current $$I = {I_o}\sin \left( {\omega t + {\pi \over 2}} \right)$$ flows through it. The average power dissipated in the circuit is

The voltage across a resistor, an inductor, and a capacitor connected in series to an ac source are 20 V, 15 V and 30 V respectively. The resultant voltage in the circuit is

A circuit is connected to an ac source of variable frequency. As the frequency of the source is increased, the current first increases and then decreases. Which of the following combinations of elements is likely to comprise the circuit?

A 15 $$\Omega$$ resistor, an 80 mH inductor and a capacitor of capacitance C are connected in series with a 50 Hz ac source. If the source voltage and current in the circuit are in phase, then the value of capacitance is