Which of the following statements about thermionic emission is NOT correct?

JAMB Physics 2023 298 views
Source: JAMB · 2023

Which of the following statements about thermionic emission is NOT correct?

  1. Thermionic emission is a process in which electrons are emitted from a metal surface due to the thermal energy of the metal.
  2. Thermionic emission is a quantum mechanical process.
  3. Thermionic emission is used in vacuum tubes and electron guns.
  4. Thermionic emission is a type of photoelectric emission. ✓
Explanation

In thermionic emission, heat gives electrons enough energy to escape a metal surface. It is used in vacuum tubes and electron guns.

Photoelectric emission is different, because light, not heat, frees the electrons. So the statement that thermionic emission is a type of photoelectric emission is wrong.

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