Electro Magnetic Induction And Alternating Currents Question 135

Question: An alternating e.m.f. of angular frequency ω is applied across an inductance. The instantaneous power developed in the circuit has an angular frequency [Roorkee 1999]

Options:

A) ω4

B) ω2

C) ω

D) 2ω

Show Answer

Answer:

Correct Answer: D

Solution:

The instantaneous values of emf and current in inductive circuit are given by

E=E0sinωt and i=i0sin(ωtπ2) respectively.

So, Pinst=Ei=E0sinωt×i0sin(ωtπ2)

=E0i0sinωt(sinωtcosπ2cosωtsinπ2)

=E0i0sinωt cosωt =12E0i0sin2ωt (sin2ωt=2sinωt cosωt)

Hence, angular frequency of instantaneous power is 2ω .



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