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In a Young's double slit experiment, the slits are separated by 0.2 mm. If the slits separation is increased to 0.4 mm, the percentage change of the fringe width is

Asked in JEE Main 4th April 1st Shift 2025 · Fringe width and fringe position

• (1) 0%
• (2) 50%
• (3) 100%
• (4) 25%

Step-by-step solution

Why the other options are wrong

• (1) Thinks fringe width does not depend on slit separation.
• (3) Takes β ∝ d so it doubles.
• (4) Takes β ∝ 1/(d²) and reports the new value as the change.

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