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Statement-1: In a standard Young's double-slit experiment with visible light, the point on the screen where the phase difference between the two waves is zero appears bright. Statement-2: At the central bright fringe of a YDSE pattern, the magnitude of the resultant electromagnetic field does not vary with time. Choose the correct option.

1. Statement-1 is true, statement-2 is false.
2. Statement-1 is true, statement-2 is true and statement-2 is the correct explanation for statement-1.
3. Statement-1 is true, statement-2 is true and statement-2 is NOT the correct explanation for statement-1.
4. Statement-1 is false, statement-2 is true.

Correct answer: Statement-1 is true, statement-2 is false.

Solution

Statement-1 is true: zero phase difference produces constructive interference, hence a bright fringe. Statement-2 is false: the electromagnetic field at any point, including the central bright fringe, still oscillates in time at the optical frequency. What is large at the bright fringe is the time-averaged intensity (amplitude), not a constant (non-varying) field. Therefore Statement-1 true, Statement-2 false.

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