Long distance short-wave radio broadcasting uses

Options

A. Ground wave
B. ionospheric wave
C. Direct wave
D. Sky wave

Answer

To solve the question "Long distance short-wave radio broadcasting uses," we need to analyze the options given and understand the principles of radio wave propagation, particularly in the context of short-wave radio broadcasting.

### Step-by-Step Solution:

1. **Understand the Concept of Short-Wave Radio Broadcasting**:
- Short-wave radio broadcasting is a method used to transmit radio signals over long distances. It operates in the frequency range of 3 to 30 MHz.

2. **Identify the Characteristics of Short-Wave Signals**:
- Short-wave signals can reflect off the ionosphere, which is a layer of the Earth's atmosphere that is ionized by solar radiation. This property allows them to travel beyond the horizon.

3. **Analyze the Options**:
- The options given are:
- Ground wave
- Ionospheric wave
- Direct wave
- Sky wave

4. **Determine the Correct Option**:
- **Ground wave**: This type of wave travels along the surface of the Earth and is typically used for lower frequency transmissions, not long-distance short-wave broadcasting.
- **Ionospheric wave**: This wave utilizes the ionosphere for reflection and refraction, making it suitable for long-distance communication.
- **Direct wave**: This wave travels in a straight line from the transmitter to the receiver, which is not effective for long distances due to the curvature of the Earth.
- **Sky wave**: This term is often used interchangeably with ionospheric wave, but it specifically refers to waves that are reflected back to Earth from the ionosphere.

5. **Conclusion**:
- The correct answer is **Ionospheric wave**, as long-distance short-wave radio broadcasting primarily relies on the ionosphere for effective signal transmission over large areas.

### Final Answer:
Long distance short-wave radio broadcasting uses **Ionospheric wave**.

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