wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

A resistance R draws power P when connected to an AC source. If an inductance is now placed in series with the resistance, such that the impedance of the circuit becomes Z, the power drawn will be


Open in App
Solution

Power of an alternating circuit

  1. Power of an alternating circuit carrying current I with resistance R, impedance V is defined by the form, P=VrmsZ2R, where, Vrms is the square the root of the time average of the voltage squared.
  2. Impedance of an LR circuit is Z=R2+ωL2, where, R is the resistance and ωL is the inductive reactance due to the inductor L.

Diagram

Power of the circuit

In the absence of the inductance, the power of the circuit is given by

P=VrmsR2R................(1).

When the inductance is connected with the resistance in series, then power is

P'=VrmsZ2R................(2)

Comparing (1) and (2) we get,

P'P=VrmsZ2RVrmsR2R=RZ2orP'=PRZ2

Therefore, the power will be P'=PRZ2.


flag
Suggest Corrections
thumbs-up
4
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Electrical Power in an AC Circuit
PHYSICS
Watch in App
Join BYJU'S Learning Program
CrossIcon