In Davisson and Germer experiment, the tungsten filament is coated with

Options

A. aluminium oxide
B. barium chloride
C. titanium oxide
D. barium oxide

Answer

**Step-by-Step Solution:**

1. **Identify the Experiment**: The question refers to the Davisson and Germer experiment, which is significant in demonstrating the wave-particle duality of electrons.

2. **Understand the Role of the Tungsten Filament**: In the experiment, a tungsten filament is used, which is a common component in vacuum tubes and electron sources.

3. **Coating of the Tungsten Filament**: The tungsten filament is coated with barium oxide. This coating is crucial for the functioning of the filament in the experiment.

4. **Reason for Coating with Barium Oxide**: Barium oxide is used because it lowers the work function of the tungsten filament. The work function is the minimum energy required to remove an electron from the surface of a material.

5. **Effect of Lowering the Work Function**: By reducing the work function, barium oxide facilitates the easier ejection of electrons from the tungsten filament. This process is known as thermionic emission.

6. **Conclusion**: Therefore, the tungsten filament in the Davisson and Germer experiment is coated with barium oxide to enhance the emission of electrons through thermionic emission.

**Final Answer**: The tungsten filament is coated with barium oxide.

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