In an A.C. circuit, the instantaneous e.m.f. and current are given by, E=100 sin30t,I=20 sin(30t- π 4). In one cycle of A.C., the average power…
JEE Main 2018 — Physics Electromagnetism
2018mcqmedium
In an A.C. circuit, the instantaneous e.m.f. and current are given by, E=100sin30t,I=20sin(30t−4π). In one cycle of A.C., the average power consumed by the circuit (in watt) and the watt-less current (in ampere) are, respectively:
Official previous-year question
Held on 8 Apr 2018 · Verified 6 Jul 2026.
Options
A
50,0
B
50,10
C
21000,10
D
250,0
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Solution
Instantaneous emf and current is given by, E=100sin30t, I=20sin(30t−4π).
Phase difference between emf and current is
ϕ=30t−(30t−4π)=4π
Average power is given by,
Pav=ErmsIrmscosϕ
=2100×220×21=21000
Watt-less current is given by,
IWL=Irmssinϕ=√2Iosin45∘⇒IWL=220.21=10A.
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