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Power Factor of RL Circuit
By BYJU'S Exam Prep
Updated on: September 25th, 2023
The power factor of an R-L circuit is 12. If the frequency of the AC input source is doubled, what will be the power factor?
A.1/√3
B.1/√7
C.1/√5
D. Remains same
select the correct answer from the above-given options.
Table of content
Answer: C.1/√5
The new power factor of an R-L circuit is 1/√5
Solution:
Power factor of r-L circuit = cosΦ=R/Z=R/[√R2+(XL)2]=1/√2
cosΦ=1/√[1+(XL/R)2]=1/√2
⇒XL/R=1
Here
L is the inductance of RL-circuit,
R is the resistance of RL-circuit,
And f is supply frequency,
If the frequency is doubled, then a new frequency applied to the RL circuit fnew=2f
Then inductive reactance across will become XL,new=ωL=2(2f)L=2.XL
Then new factor for frequency fnew will be P.Fnew=1/√[1+(2.XL/R)2]=1/√[1+4]=1/√5