The phenomena involved in the reflection of radio waves by ionosphere are similar to

Options

A. reflection of light by a plane mirror.
B. total internal reflection of light in air during a mirage.
C. dispersion of light by water molecules during the formation of a rainbow.
D. scattering of light by theparticles of air.

Explanation

To solve the question regarding the phenomena involved in the reflection of radio waves by the ionosphere, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Ionosphere**: The ionosphere is a region of the Earth's upper atmosphere, which is ionized by solar and cosmic radiation. It reflects radio waves back to the Earth's surface, allowing for long-distance communication.

2. **Identifying the Phenomenon**: The reflection of radio waves by the ionosphere can be compared to the behavior of light when it encounters different mediums. In this case, we need to identify a similar optical phenomenon.

3. **Total Internal Reflection**: The phenomenon that closely resembles the reflection of radio waves by the ionosphere is called **total internal reflection**. This occurs when a wave (like light) travels from a denser medium to a rarer medium and hits the boundary at an angle greater than the critical angle, resulting in the wave being completely reflected back into the denser medium.

4. **Conditions for Total Internal Reflection**:
- The wave must be traveling from a medium with a higher refractive index (denser medium) to a medium with a lower refractive index (rarer medium).
- The angle of incidence must be greater than the critical angle for the two mediums.

5. **Conclusion**: Therefore, the phenomena involved in the reflection of radio waves by the ionosphere are similar to total internal reflection, as both involve the reflection of waves when transitioning between mediums of different densities.

### Final Answer:
The phenomena involved in the reflection of radio waves by the ionosphere are similar to **total internal reflection**.

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