Statement-I : In Young's double slit experiment interference pattern dissappears when one of the slits is closed
Statement-II : Interference is observed due to superposition of light waves from two coherent source

Options

A. Statement-1 is true, statement-2 is true: Statement-2 is a correct explanation for statement-1
B. Statement-2 is true, statement-2 is true: statement-2 is not a correct explanation for statement-1
C. Statement-1 is true, Statement-2 is false.
D. Statement-1 is false, Statement-2 is true.

Answer

To solve the question, we need to analyze both statements provided:

**Statement-I:** In Young's double slit experiment, interference patterns disappear when one of the slits is closed.

**Statement-II:** Interference is observed due to superposition of light waves from two coherent sources.

### Step-by-Step Solution:

1. **Understanding Young's Double Slit Experiment (YDSE):**
- In YDSE, light from a coherent source passes through two closely spaced slits, creating an interference pattern on a screen due to the superposition of light waves emanating from the two slits.

2. **Analyzing Statement-I:**
- If one of the slits is closed, only one slit remains open.
- With only one slit open, there is no second wave to interfere with the wave coming from the open slit.
- Therefore, the interference pattern, which relies on the interaction of two waves (constructive and destructive interference), will indeed disappear when one slit is closed.
- **Conclusion for Statement-I:** True.

3. **Analyzing Statement-II:**
- Interference is a phenomenon that occurs when two or more waves overlap and combine.
- For interference to be observed, the waves must be coherent, meaning they have a constant phase difference and the same frequency.
- In YDSE, the light waves coming from the two slits are coherent sources, leading to the formation of an interference pattern.
- **Conclusion for Statement-II:** True.

4. **Relationship Between the Statements:**
- Statement-II explains why Statement-I is true. The disappearance of the interference pattern when one slit is closed is due to the lack of a second coherent wave to interfere with the first.
- **Conclusion:** Statement-II is the correct explanation for Statement-I.

### Final Conclusion:
Both statements are true, and Statement-II is the correct explanation for Statement-I.