Neet Solved Paper 2015 Question 34
Question: A resistance R draws power P when connected to an AC source. If an inductance such that the impedance of the circuit becomes Z the power drawn will the
Options:
A) $ P{{( \frac{R}{Z} )}^{2}} $
B) $ P\sqrt{\frac{R}{Z}} $
C) $ P( \frac{R}{Z} ) $
D) P
Show Answer
Answer:
Correct Answer: A
Solution:
- When a resistor is connected to an AC source. The power drawn will be $ p=V _{rms}/I _{rms}=V _{rms}.\frac{V _{rms}}{R} $
$ \Rightarrow ,V_rms^{2}=PR $ When an inductor is connected in series with the resistor, then the power drawn will be $ P’=V _{rms}.I _{rms}\cos \phi $ where, $ \phi $ = phase difference
$ \therefore $ $ P’=\frac{V_rms^{2}}{R}.\frac{R^{2}}{Z^{2}}=p.R.\frac{R}{Z^{2}} $
$ \Rightarrow ,p’=\frac{p.R^{2}}{Z^{2}}=P{{( \frac{R}{Z} )}^{2}} $
