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Question: Answered & Verified by Expert
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:
PhysicsAlternating CurrentJEE MainJEE Main 2018 (08 Apr)
Options:
  • A 50, 0
  • B 50, 10
  • C 10002, 10
  • D 502, 0
Solution:
1434 Upvotes Verified Answer
The correct answer is: 10002, 10

Instantaneous emf and current is given by, E=100sin30tI=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=Io2sin45°IWL=202.12=10 A.

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