Alternating Current

JEE Main level, single correct, medium

73 of 190

Question 73 of 190

In series LCR circuit, the capacitance is changed from CC to 4C4C. To keep the resonance frequency unchanged, the new inductance should be :

Show answer and solution

Answer: (C) reduced by 34L\dfrac{3}{4}L

As resonance frequency remains unchanged, therefore ω′=ω\omega '=\omega
⇒1L′C′=1LC\Rightarrow \dfrac{1}{\sqrt{L'C'}}=\dfrac{1}{\sqrt{LC}}
⇒L′C′=LC\Rightarrow L'C'=LC
⇒L′(4C)=LC\Rightarrow L'\left(4C\right)=LC
⇒L′=L4\Rightarrow L'=\dfrac{L}{4}
∵∵ Inductance must be decreased by 3L4\dfrac{3L}{4}.

JEE Main question paper PDF

Open a shift to read the full paper on this page, or download it.

JEE Main 2025 Apr 2 Shift 1 question paper

Open Download PDF

Opening paper…

Explain it as a whiteboard videoStep-by-step, in Hinglish or English. Your first video needs no login.Solved it on paper but got it wrong?Upload a photo of your working. Mistake Doctor marks the exact line that broke.
See it move: AC circuits, phasors and resonance simulationDrag the sliders and watch the numbers in this question change.

More Physics practice

JEE Main Physics practice question on Alternating Current (AC Circuits), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.