Which of the following devices is half duplex ?

Options

A. Mobile phone
B. Walky-talky
C. Loud speaker
D. Radio

Answer

To determine which device is half-duplex among the given options (mobile phone, walkie-talkie, loudspeaker, radio), we first need to understand the definitions of half-duplex and full-duplex communication systems.

### Step-by-Step Solution:

1. **Understand Full-Duplex Communication:**
- In a full-duplex system, both devices can transmit and receive signals simultaneously. For example, when two people are talking on a mobile phone, both can speak and listen at the same time.

2. **Understand Half-Duplex Communication:**
- In a half-duplex system, devices can either transmit or receive signals, but not both at the same time. For example, in a walkie-talkie, one person must finish speaking before the other can respond.

3. **Analyze the Options:**
- **Mobile Phone:** This is a full-duplex device because it allows simultaneous talking and listening.
- **Walkie-Talkie:** This is a half-duplex device because it requires one person to wait for the other to finish speaking before responding.
- **Loudspeaker:** This is a full-duplex device as it can play sound while receiving signals (e.g., from an amplifier).
- **Radio:** This is also a full-duplex device as it can receive signals while playing audio.

4. **Identify the Half-Duplex Device:**
- Among the options, the only device that operates in half-duplex mode is the **walkie-talkie**.

### Conclusion:
The device that is half-duplex is the **walkie-talkie**.

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