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Question: Answered & Verified by Expert
In a series L.C.R circuit, the potential drop across \( L, C \) and \( R \) respectively are \( 40 \mathrm{~V}, 120 \mathrm{~V} \) and
\( 60 \mathrm{~V} \). Then the source voltage is
PhysicsAlternating CurrentKCETKCET 2016
Options:
  • A \( 220 \mathrm{~V} \)
  • B \( 160 \mathrm{~V} \)
  • C \( 180 \mathrm{~V} \)
  • D \( 100 \mathrm{~V} \)
Solution:
1455 Upvotes Verified Answer
The correct answer is: \( 100 \mathrm{~V} \)
Given, voltage drop across \( \mathrm{L}, V_{L}=40 \mathrm{~V} ; \) voltage dropacross \( \mathrm{C}, V_{c}=120 \mathrm{~V} ; \) voltage drop across \( R, V_{R}=60 \mathrm{~V} \)

Then source voltage \( =\sqrt{{V_{R}}^{2}+\left(V_{L}-V_{C}\right)^{2}} \)
\( =\sqrt{60^{2}+(120-40)^{2}} \)
\( =\sqrt{3600+6400} \)
\( =\sqrt{10000} \)
\( =100 \mathrm{~V} \)
Therefore, source voltage \( =100 \mathrm{~V} \)

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