JEE Main 2018PhysicsAlternating CurrentMediumMCQ

JEE Main 2018 — Alternating Current Question with Solution

JEE Main 2018 (08 Apr)

Question

In an A.C. circuit, the instantaneous e.m.f. and current are given by, E=100sin30t,I=20sin30t-π4. In one cycle of A.C., the average power consumed by the circuit (in watt) and the watt-less current (in ampere) are, respectively:

Choose an option

Show full solutionCorrect option: C
Correct answer
C10002, 10

Step-by-step explanation

Instantaneous emf and current is given by, E=100sin30t, I=20sin30t-π4.

Phase difference between emf and current is 

ϕ=30t-30t-π4=π4

Average power is given by,

 Pav=ErmsIrmscosϕ
=1002×202×12=10002



Watt-less current is given by, 

IWL=Irmssinϕ=Io√2sin45°⇒IWL=202.12=10 A.

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About this question

This is a previous-year question from JEE Main 2018, 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.