Question
Five cells each of emf E and internal resistance r send the same amount of current through an external resistance R whether the cells are connected in parallel or in series. Then the ratio ( R r ) is
BITSAT
Physics
Current Electricity
2024
BITSAT 2024 (Memory Based Paper 1)
BITSAT Physics Question (2024) — Solution
Options
- A. 2
- B. 1 2
- C. 1 5
- D. 1
Answer
D. 1
Step-by-step solution
Given : Number of cells, n=5, emf of each cell =E Internal resistance of each cell =r In series, current through resistance R I= n E n r+R = 5 E 5 r+R In parallel, current through resistance R I^ = E r n +R = n E r+n R = 5 E r+5 R According to question, I=I^ 5 E 5 r+5 R = 5 E r+5 R 5 r+R=r+5 R or R=r R r =1
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