The waves that are bent down by the ionosphere are

Options

A. ground waves
B. surface waves
C. space waves
D. sky waves

Explanation

To solve the question "The waves that are bent down by the ionosphere are", we need to analyze the types of waves in relation to the ionosphere's behavior. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Ionosphere
The ionosphere is a region of the Earth's upper atmosphere, which is ionized by solar and cosmic radiation. It plays a crucial role in radio wave propagation.

**Hint:** The ionosphere can reflect certain radio waves back to Earth, which is essential for long-distance communication.

### Step 2: Identify Wave Types
There are different types of waves used in communication:
- **Ground Waves:** These travel along the surface of the Earth.
- **Surface Waves:** These are similar to ground waves but are typically associated with lower frequencies.
- **Space Waves:** These travel directly from the transmitter to the receiver without being reflected.
- **Sky Waves:** These are radio waves that are reflected back to Earth by the ionosphere.

**Hint:** Consider which type of wave would interact with the ionosphere.

### Step 3: Analyze Wave Behavior with the Ionosphere
Sky waves are specifically designed to be reflected by the ionosphere. When transmitted, they can travel long distances by bouncing off the ionosphere back to the Earth, allowing for communication over vast distances.

**Hint:** Think about how communication systems utilize the ionosphere for long-range signals.

### Step 4: Conclusion
Based on the analysis, the waves that are bent down by the ionosphere are indeed **sky waves**. This is because they can be reflected back to Earth, enabling communication over long distances.

**Final Answer:** The waves that are bent down by the ionosphere are **sky waves**.

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