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Question: Answered & Verified by Expert
One end each of a resistance \( r \), capacitor \( C \) and resistance \( 2 r \) are connected together. The other ends are respectively connected to the positive terminals of batteries, \( P, Q, R \) having, respectively, emf's \( E, E \) and \( 2 E \). The negative terminals of the batteries are then connected together. In this circuit, with steady current the potential drop across the capacitor is,
PhysicsCurrent ElectricityJEE Main
Options:
  • A \( \frac{E}{3} \)
  • B \( \frac{E}{2} \)
  • C \( \frac{2 E}{3} \)
  • D \( E \)
Solution:
1537 Upvotes Verified Answer
The correct answer is: \( \frac{E}{3} \)
In the steady state, no current flows through the capacitor branch.

In the steady state, the middle branch having the capacitor acts as an open switch and hence, the effective emf of the circuit in the steady state is E+2E=3E and the current in the circuit is,
i=net emfnet resistance
   =2E-Er+2r=E3r
So, potential drop across capacitor is,
V=ir=E3r×r=E3

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