If yellow light emitted by sodium lamp in Young’s double-slit experiment is replaced by monochromatic blue light of same intensity:
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Question

If yellow light emitted by sodium lamp in Young’s double-slit experiment is replaced by monochromatic blue light of same intensity:

G1 Physics · Accepted Answer

Step 1: YDSE fringe width β = λD/d. Step 2: Blue light has shorter wavelength than sodium yellow light. Step 3: Smaller λ gives smaller fringe width at fixed D and d. Final answer: (A) fringe width decreases.