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

$E$

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 $2$), 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.