The power factor of an a.c. circuit is 0.5. what will be the phase difference between voltage and the current?

Average power of an a.c. circuit is:

In a series LCR circuit the voltage across an inductor, a capacitor and a resistor are 20V, 20V and 40V respectively. What is the phase difference between the applied voltage and the current in the circuit?

An a.c. Voltage is applied to a resistance R=30 Omega and an inductor L in series. If the inductive reactance is also 30 Omega , the phase difference between the applied voltage and the current in the circuit is

What do you mean by power factor of an a.c. circuit ?

An LCR-circuit is connected to a source of a.c. current under resonant condition. The phase difference between the applied voltage and the current it the circuit is

In a series LCR circuit the voltage across an inductor, a capacitor and a resistor are 30V, 30V and 60V respectively. What is the phase difference between the applied voltage and current in the circuit?