Thermionic Electron Emission

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Thermionic Emission of Electrons

Materials used for thermionic emission are typically transition metals or their carbides or borides.

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Thermionic emission

  • Thermionic emission is when a metal will release electrons when it is heated.
  • This term can be broken down:
    • “Therm-” means that this process relates to heating.
    • “-ionic-” means that this process relates to charge.
    • “-emission” means that the process will emit something.
    • All together, the term means emitting charged particles when heated.
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Work done on an accelerated electron

  • An electron charge, e, accelerated by a potential difference, V, gains energy eV.
  • Thus the energy gained:
    • eV=12mv2eV = \frac12 mv^2
  • From which the velocity of the electron can be calculated.
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Uses of thermionic emission

  • Thermionic emitted electrons can be used in electron guns.
    • An electric field is used to accelerate particles to a high velocity.
    • By using a small hole in the anode, a narrow electron beam (cathode ray) can be produced.

Jump to other topics

1Measurements & Errors

2Particles & Radiation


4Mechanics & Materials


6Further Mechanics & Thermal Physics (A2 only)

7Fields & Their Consequences (A2 only)

8Nuclear Physics (A2 only)

9Option: Astrophysics (A2 only)

10Option: Medical Physics (A2 only)

11Option: Engineering Physics (A2 only)

12Option: Turning Points in Physics (A2 only)

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