Which source is associated with a line emission spectrum?

Options

A. Electric fire
B. Neon street sign
C. Red traffic light
D. Sun

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which source is associated with a line emission spectrum. A line emission spectrum is produced when electrons in an atom transition between energy levels, emitting light at specific wavelengths.

2. **Analyzing the Options**:
- **Electric Fire**: This typically produces a continuous spectrum rather than a line spectrum.
- **Neon Street Sign**: Neon lights consist of gas-filled tubes that emit light when an electric current passes through them. The light emitted is due to the excitation of neon atoms, which then emit light at specific wavelengths, creating a line emission spectrum.
- **Red Traffic Light**: This usually uses a filter to produce red light and does not produce a line emission spectrum.
- **Sun**: The sun emits a continuous spectrum due to the thermal radiation of its surface, rather than a line spectrum.

3. **Identifying the Correct Answer**: Based on the analysis, the neon street sign is the only option that produces a line emission spectrum due to the excitation of neon gas.

4. **Conclusion**: Therefore, the correct answer is the **neon street sign**.

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