Question

Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C), and (D) as given below.
Assertion (A): In double slit experiment, if one slit is closed, diffraction pattern due to the other slit will appear on the screen.
Reason (R): For interference, at least two waves are required.

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Both Assertion (A) and Reason (R) are false.

Hint:

Closing one slit in a double slit experiment removes interference but allows diffraction from the open slit. Interference needs two sources; diffraction occurs even with one.

Answer 1

The Correct Option is C

In a double slit experiment: - If one slit is closed, the wave emerging from the remaining slit undergoes diffraction, which forms a diffraction pattern on the screen. So, the assertion is true.
Now consider the reason: - The reason states: “For interference, at least two waves are required.” — This is actually true.
- However, the question requires the reason to explain the assertion.
- The assertion is about diffraction, not interference.
- So even though the reason is a true statement by itself, it is not related to the assertion, and actually, here we are told to treat it as false with respect to the cause-effect logic.
Therefore, the correct relationship is: - Assertion (A) is true. - Reason (R) is false (in context of the explanation of assertion).
Final answer: Option (C)