Which one of the following metals is used in the filaments of photo-electric cells that convert light into electric energy ?

Options

A. Tungsten
B. Copper
C. Rubidium
D. Aluminium

Explanation

**Step-by-Step Solution:**

1. **Understanding Photoelectric Cells:**
- Photoelectric cells are devices that convert light energy into electrical energy. They work on the principle of the photoelectric effect, where light photons can dislodge electrons from a material, generating an electric current.

2. **Identifying the Function of Filaments:**
- The filament in a photoelectric cell plays a crucial role in the conversion process. It needs to have specific properties, such as high resistance and low leakage of current, to effectively convert light into electric energy.

3. **Researching Suitable Metals:**
- Various metals can be used in the construction of filaments for photoelectric cells. However, not all metals possess the necessary properties for optimal performance in this application.

4. **Determining the Correct Metal:**
- Among the metals that can be used, rubidium is identified as a suitable choice. Rubidium has high resistance and low leakage of current, making it an ideal filament material for photoelectric cells.

5. **Conclusion:**
- Therefore, the metal used in the filaments of photoelectric cells that convert light into electric energy is **rubidium**.

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