JEE Main 2025 Jan 22 Shift 2, Physics Q15: Young’s Double Slit Experiment
Given below are two statements. On is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : In Young's double slit experiment, the fringes produced by red light are closer as compared to those produced by blue light.
Reason (R) : The fringe width is directly proportional to the wavelength of light.
In the light of above statements, choose the correct answer from the options given below :
- A
Both (A) and (R) are true and (R) is the correct explanation of (A)
- 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.
In Young's double slit experiment, fringe width is , which is directly proportional to wavelength. So (R) is true.
Red light has a larger wavelength than blue light: . Therefore , meaning red fringes are wider apart, not closer.
The assertion claims red fringes are closer than blue, which is the opposite of what theory predicts. So (A) is false.
(A) is false but (R) is true.
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