NEETPhysicsAlternating Current
Given below are two statements: Statement I : When the frequency of an AC source in a series LCR circuit increases, the current in the circuit first increases, attains a maximum value and then decreases. Statement II : In a series LCR circuit, the value of power factor at resonance is one. In the light of given statements, choose the most appropriate answer from the options given below.
Options
- AStatement I is incorrect but Statement II is true
- BBoth Statement I and Statement II are false
- CBoth Statement I and Statement II are true
- DStatement I is correct but Statement II is false
Correct answer
C. Both Statement I and Statement II are true
Step-by-step solution
When an a.c. voltage is applied in a series LCR circuit, the current is increased first, attains a maximum and then decreases. The formula to calculate the power factor is given by cos ϕ = R R 2 + X L 2 - X C 2 . . . 1 At resonance, X L = X C , Hence, cos ϕ resonance = 1 Thus, both the statements are true.