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A resistance R draws power P when connec...

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:

A

`P(R/Z)^2`

B

`Psqrt(R/Z)`

C

`P(R/Z)`

D

P

Text Solution

Verified by Experts

The correct Answer is:
A
The rms current in the first and second cases are `I=E/R`and `I'=E/Z`, respectively.
`therefore` Pure inductor does not draw any power, then the respective powers drawn the
`P=I^2R=(E/R)^2R=E^2/R`
and `P'=I'^2R=(E/Z)^2R=E^2/R(R/Z)^2=P(R/Z)^2`
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