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QPage 351: Q4: HC Verma: Concepts of Physics - Volume 2 Electric Current through Gases Page 351: Q4 Solution: Would you prefer a material with a high melting point or a low…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students often mistake a low melting‑point material as being better for thermionic emission, conflating melting point with the work‑function or required emission temperature; however, the cathode must remain solid at the high operating temperature, so a high melting‑point material is essential.

Would you prefer a material with a high melting point or a low melting point to be used as a cathode in a diode?

Step-by-Step Verified Solution

**Answer:** A material with a high melting point is preferred. **Step-by-Step Explanation:** The cathode in a diode operates at high temperatures to emit thermions. If the melting point is low, the cathode would melt or vaporise. A high melting point ensures the cathode can withstand the operating temperature without damage .

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