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JEE MainPhysicsCurrent Electricity

Two cells are connected in opposition in a single closed loop with no external resistors. The first cell has an emf of 15 V and an internal resistance of 3 . The second cell has an emf of 5 V and an internal resistance of x . If the terminal potential difference across the first cell is 9 V , the value of x is ______.

Correct answer

2

Step-by-step solution

Let the current in the circuit be I . The first cell is discharging because its emf is greater than that of the second cell. The terminal potential difference across a discharging cell is given by V₁ = E₁ - I r₁ . Substituting the given values: 9 = 15 - I(3) 3I = 6 I = 2 A Since the two cells form a single closed loop with no other components, the terminal potential difference across the second cell must be equal to that across the first cell. Thus, V₂ = 9 V . The second cell is being charged by the first cell, so

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