Two cells each of emf E and internal resistance r are connected in such a way that their positive terminals are connected to point X and negative terminals are connected to point Y. The potential difference between X and Y is
Answer & explanation
Correct answer: option 3
The correct answer is Option (1) → zero
Note: The given answer is as per NTA. However, there seems be a mistake in the NTA answer. The correct answer should be Option 3 and not Option 1 as given by nTA as explained below.
Both cells are connected in parallel (positive to X and negative to Y).
In a parallel combination of identical cells:
- The emf remains the same as that of one cell
- The internal resistance reduces (becomes r/2), but that does not affect the emf value across the terminals
- So, the effective emf between X and Y = E.
Parallel connection does not add emfs → hence the potential difference is E, not 2E.