Double slit with one slit closed – Rankers Physics

Young's Double Slit Experiment: Practice Problem & Solution

Assertion (A): In the double slit experiment, if one of the slit is closed, no fringe pattern will be observed on the screen. Reason (R): In interference, phenomenon of diffraction is also included.
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Young's Double Slit Experiment. Understanding the underlying formula is key to arriving at the correct answer below:

Assertion (A) is true: If one slit is closed, the two-source condition for interference is not met, so a distinct interference fringe pattern is not observed. Instead, a single-slit diffraction pattern appears. Reason (R) is true: The observed double-slit intensity pattern is a combination of interference from two slits and diffraction from each individual slit. Both (A) and (R) are true, but (R) is not the correct explanation for (A).

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