JEE Main 2019PhysicsAlternating CurrentMediumMCQ

JEE Main 2019 — Alternating Current Question with Solution

JEE Main 2019 (12 Apr Shift 2)

Question

Consider the LR circuit shown in the figure. If the switch S is closed at t=0 then the amount of charge that passes through the battery between t=0 and t=LR is:

Choose an option

Show full solutionCorrect option: D
Correct answer
D EL2.7R2

Step-by-step explanation

The current in the LR circuit at any time t is
I=ER1-e-RtL

Where E, R, L, I are the EMF, resistance, inductance and the current respectively.
∴ Charge flown through the circuit from time 0 to LR is 
(charge) ∆q=∫0LRI.dt=∫0LRER1-e-RtLdt
⇒∆q=ERt+LR e-RtL0LR
⇒∆q=ERLR+LRe-1-LR
⇒∆q=ER×LeR
⇒∆q=ELeR2=EL2.7R2

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About this question

This is a previous-year question from JEE Main 2019, covering the Alternating Current chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.