JEE Main202127 Aug 2021Morning ShiftPhysicsCurrent ElectricityActual
Five identical cells each of internal resistance 1 Ω and emf 5 V are connected in series and in parallel with an external resistance R . For what value of R , current in series and parallel combination will remain the same?
Options
- A1   Ω
- B5   Ω
- C25   Ω
- D10   Ω
Correct answer
A. 1   Ω
Step-by-step solution
i 1 = 5 ε R + 5 r       . . . 1 I 2 = ε R + r 5       . . . 2 From equation 1 and 2 i 1 = i 2 5 ε R + 5 r = ε R + r 5 ⇒ R = r = 1 Ω