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Question: Answered & Verified by Expert
In a series, $L-C-R$ circuit
PhysicsAlternating CurrentAP EAMCETAP EAMCET 2020 (22 Sep Shift 1)
Options:
  • A the voltage leads the current if $X_L < X_C$
  • B the voltage leads the current if $X_L>X_C$
  • C the voltage and current are in phase
  • D the current leads the voltage if $X_L>X_C$
Solution:
2139 Upvotes Verified Answer
The correct answer is: the voltage leads the current if $X_L>X_C$
Phasor diagram of $L-C-R$ series circuit is shown in the following figure,




For phasor diagram, it is clear that if $V_L>V_C$, then voltage $V$ leads $\phi$ angle from current.
where, $\phi=\tan ^{-1}\left(\frac{V_L-V_C}{V_R}\right)=\tan ^{-1}\left(\frac{X_L-X_C}{R}\right)$
Hence, voltage leads the current with angle $\phi$, when
$$
V_L>V_C \Rightarrow I X_L>I X_C \Rightarrow X_L>X_C
$$

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