Assertion : The twinkling of star is due to rcfiectiop of light
Reason : The velocity of light changes while going from one medium to the other.

Options

A. If both assertion and reason are true and\ reason is a correct explanation of the assertion
B. If both assertion and reason are true but the reason is not a correct explanation of assertion.
C. If assertion is true but reason is false.
D. If assertion is false but reason is true

Answer

To solve the assertion-reason question, we will analyze both the assertion and the reason separately.

### Step 1: Analyze the Assertion
The assertion states: "The twinkling of stars is due to reflection of light."

- **Explanation**: Twinkling of stars is not caused by reflection; it is primarily due to the refraction of light. Stars are located at vast distances, and as the light from these stars travels through the Earth's atmosphere, it passes through layers of air with varying densities. Each layer has a different refractive index, which causes the light to bend (refract) as it moves from one layer to another. This bending of light results in the apparent position of the star changing slightly, leading to the twinkling effect.

### Step 2: Analyze the Reason
The reason states: "The velocity of light changes while going from one medium to the other."

- **Explanation**: This statement is correct. When light travels from one medium to another (for example, from air to water), its speed changes due to the difference in the refractive index of the two media. The refractive index is defined as the ratio of the speed of light in vacuum (or air) to the speed of light in the medium. Therefore, a change in the refractive index indicates a change in the velocity of light.

### Step 3: Conclusion
- The assertion is **false** because twinkling is due to refraction, not reflection.
- The reason is **true** because the velocity of light does change when it moves between different media.

### Final Answer
Since the assertion is false and the reason is true, the correct option is that the assertion is incorrect while the reason is correct.