Alternating Current - Result Question 16

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16. 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

======= ####16. 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

3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed:content/english/neet-pyq-chapterwise/physics/alternating-current/alternating-current—result-question-16.md (a) $P \sqrt{\frac{R}{Z}}$

(b) $P(\frac{R}{Z})$

(c) $P$

(d) $P(\frac{R}{Z})^{2}$

[2015]

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Answer:

Correct Answer: 16. (d)

Solution:

  1. (d)

Pure resistor L-R series circuit

Phasor diagram

For pure resistor circuit, power

$ P=\frac{V^{2}}{R} \Rightarrow V^{2}=PR $

For L-R series circuit, power

$ P^{1}=\frac{V^{2}}{Z} \cos \theta=\frac{V^{2}}{Z} \cdot \frac{R}{Z}=\frac{PR}{Z^{2}} \cdot R=P(\frac{R}{Z})^{2} $