NEETPhysicsWave Optics
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): In a Young's double slit experiment, if the screen is moved away from the plane of the slits, the angular separation of the fringes remains constant. Reason (R): The linear fringe width increases as the screen distance increases, but the angular fringe width depends only on the wavelength of light
Options
- ABoth Assertion (A) and Reason (R) are correct but Reason (R) is not the correct explanation for Assertion (A).
- BBoth Assertion (A) and Reason (R) are correct and Reason (R) is the correct explanation for Assertion (A).
- CAssertion (A) is correct but Reason (R) is incorrect.
- DAssertion (A) is incorrect but Reason (R) is correct.
Correct answer
B. Both Assertion (A) and Reason (R) are correct and Reason (R) is the correct explanation for Assertion (A).
Step-by-step solution
The linear fringe width in Young's double slit experiment is given by = D d , where is the wavelength, D is the distance to the screen, and d is the slit separation. The angular fringe width is given by = D = d . When the screen is moved away from the plane of the slits, the distance D increases. This causes the linear fringe width to increase. However, the angular fringe width depends only on and d , so it remains independent of D . Therefore, both Assertion (A) and Reason (R) are correct, and Reason (R) provides