From which layer of atmosphere radio and microwaves are reflected back? 

Answer

**Step-by-Step Solution:**

1. **Understanding the Atmosphere Layers**: The Earth's atmosphere is divided into several layers, including the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Each layer has different properties and plays a role in various phenomena.

2. **Identifying the Ionosphere**: Among these layers, the ionosphere is a significant layer that is located within the thermosphere and extends from about 30 miles (48 kilometers) to 600 miles (965 kilometers) above the Earth's surface. It is characterized by a high concentration of ions and free electrons.

3. **Role of the Ionosphere in Communication**: The ionosphere is crucial for radio and microwave communication. It reflects certain radio waves back to the Earth, allowing for long-distance communication. This reflection occurs because the ionized particles in the ionosphere can reflect electromagnetic waves, particularly those in the radio and microwave frequency ranges.

4. **Conclusion**: Therefore, the layer of the atmosphere from which radio and microwaves are reflected back is the **ionosphere**. This reflection is essential for communication technologies such as radio broadcasting and satellite communication.

**Final Answer**: The ionosphere.

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