Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): If Young's double slit experiment is performed in an optically denser medium than air, then the consecutive fringes come closer.
Reason (R): The speed of light reduces in an optically denser medium than air while its frequency does not change.
In the light of the above statements, choose the most appropriate answer from the options given below:
Assertion (A): If Young's double slit experiment is performed in an optically denser medium than air, then the consecutive fringes come closer.
Reason (R): The speed of light reduces in an optically denser medium than air while its frequency does not change.
In the light of the above statements, choose the most appropriate answer from the options given below:
- (A)Both (A) and (R) are true and (R) is the correct explanation of (A)✓ Correct
- (B)(A) is false but (R) is true.
- (C)Both (A) and (R) are true but (R) is not the correct explanation of (A)
- (D)(A) is true but (R) is false.
Answer: (A)
Solution
Fringe width in Young's double slit experiment is . In a medium of refractive index , the wavelength shortens to , since while the frequency, set by the source, stays the same, so scales down with . A smaller means a smaller , so the fringes come closer together — Assertion (A) is true, and Reason (R), which correctly explains why shrinks, accounts for it.
Both (A) and (R) are true, and (R) is the correct explanation of (A).
Both (A) and (R) are true, and (R) is the correct explanation of (A).
JEE Main · 2025 · 22 Jan 2025 · Shift 1 · Single correct option