To analyze the assertion and reason provided in the question, we will break down the concepts step by step.
### Step-by-Step Solution:
1. **Understanding the Assertion (A)**:
- The assertion states that in the case of a rainbow, light at the inner surface of the water drop gets internally reflected. This is true because when sunlight enters a water droplet, it undergoes refraction and then reflects internally before exiting the droplet.
2. **Understanding the Reason (R)**:
- The reason states that the angle between the refracted ray and the normal to the drop surface is greater than the critical angle. This is also true because for total internal reflection to occur, the angle of incidence must be greater than the critical angle for the water-air interface.
3. **Formation of a Rainbow**:
- When sunlight enters a water droplet, it is refracted (bent) due to the change in medium (from air to water). This bending of light causes dispersion, separating the white light into its constituent colors (red, orange, yellow, green, blue, indigo, violet).
- After refraction, the light hits the inner surface of the droplet. If the angle of incidence is greater than the critical angle, total internal reflection occurs, and the light reflects back inside the droplet.
4. **Exit of Light**:
- The internally reflected light then refracts again as it exits the droplet into the air. This second refraction further separates the colors, creating the spectrum seen in a rainbow.
5. **Conclusion**:
- Both the assertion and the reason are true, and the reason correctly explains the assertion. Therefore, the formation of a rainbow is dependent on the internal reflection of light within the water droplet, which occurs when the angle of incidence exceeds the critical angle.
### Final Answer:
- **Assertion (A)**: True
- **Reason (R)**: True
- **Explanation**: The reason correctly explains the assertion.
---
