Question

If the frequency of the ac source in a series LCR-circuit is increased, how does the current in the circuit change?

(a) Decreases then increase

(b) Increases then decrease

(c) Becomes zero

(d) Remains constant

This question was posed to me during an internship interview.

My enquiry is from AC Voltage Applied to a Series LCR Circuit topic in portion Alternating Current of Physics – Class 12

Answer 1

Correct answer is (b) Increases then decrease

To explain: With the increase in frequency, the current in a series LCR circuit undergoes a series of changes, i.e. the current in a series LCR-circuit first increases, attains a maximum value (at f = fr) and then decreases.