JEE MainPhysicsCurrent Electricity
Two cells are connected in series such that their positive terminals are joined together. The first cell has an emf of 20 V and an internal resistance of 2 . The second cell has an emf of 4 V and an internal resistance of 1 . Their free negative terminals are connected across an external resistor of 5 to form a single closed loop. The terminal potential difference of the second cell is ______ V .
Correct answer
6
Step-by-step solution
The two cells are connected in opposition. The net emf in the circuit is the difference between their individual emfs. Net emf, E_ net = E₁ - E₂ = 20 - 4 = 16 V The total resistance of the circuit is the sum of the internal resistances and the external resistance. Total resistance, R_ total = r₁ + r₂ + R = 2 + 1 + 5 = 8 The current in the circuit is: I = E_ net R_ total = 16 8 = 2 A The current flows out of the positive terminal of the first cell and into the positive terminal of the second cell. Therefore, the sec