(a) Define the term power factor for an alternating-current circuit. (b) Explain…
PHYSICS · Subjective · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
(a) Define the term power factor for an alternating-current circuit.
(b) Explain briefly why the power factor is an important index for electrical appliances connected to the mains.
(c) Under what condition is the current in a circuit said to be wattless? Give one practical example.
(d) A lamp rated at 100 W, 230 V is to be operated on an A.C. supply of 230 V, 50 Hz through a choke coil instead of a pure resistor. Explain, with reasons, whether the power factor of the lamp–choke combination should be high or low so that the arrangement works satisfactorily.
(e) State two possible methods that can be adopted in an industrial installation to improve the overall power factor of the load.
(Note: Answer all parts in sequence. Each part carries separate marks.)