Which of the following statements on alternating current circuits are true?
A. In circuits with primarily inductive loads, the current leads the voltage.
B. The ratio of resistance to impedance of A.C. circuit is known as power factor of the circuit.
C. Two alternating quantities reach their maximum or minimum value at different time, keeping any equal phase angle between them are called 'in phase'
D. The steady state d.c. current which produce the same heat as that produced by alternating current in a given time and given resistance is known as the root mean square value of alternating current.
Choose the most appropriate answer from the options given below: