A small air bubble in a glass block when seen from above appears to be raised because of :

Options

A. refraction of light
B. reflection of light
C. reflection and refraction of light
D. none of the above

Answer

### Step-by-Step Solution:

1. **Understanding the Scenario**:
- We have a small air bubble located within a glass block. The bubble is surrounded by glass, which is a denser medium compared to air.

2. **Identifying the Observation Point**:
- The bubble is viewed from above the glass block. This means that light from the bubble travels through the glass before reaching the observer's eyes.

3. **Analyzing the Mediums**:
- The light travels from a denser medium (glass) to a rarer medium (air). In this case, the glass block is the denser medium, and the air bubble is the rarer medium.

4. **Applying the Law of Refraction**:
- According to the law of refraction (Snell's Law), when light passes from a denser medium to a rarer medium, it bends away from the normal line. The normal line is an imaginary line perpendicular to the surface at the point of incidence.

5. **Visualizing the Bending of Light**:
- As light rays from the bubble enter the air, they bend away from the normal. This bending causes the bubble to appear at a different position than its actual location.

6. **Conclusion**:
- Because of this bending of light due to refraction, the air bubble appears to be raised when viewed from above. Therefore, the correct answer to the question is that the bubble appears raised because of the refraction of light.

### Final Answer:
The small air bubble in a glass block appears to be raised because of **refraction of light**.

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