Thermionic Electron Emission
Physics: AQA A Level, topic 12.1.2
Thermionic Emission of Electrons
Materials used for thermionic emission are typically transition metals or their carbides or borides.
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.
Work done on an accelerated electron
- An electron charge, e, accelerated by a potential difference, V, gains energy eV.
- Thus the energy gained:
- From which the velocity of the electron can be calculated.
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.
Test yourself on Thermionic Electron Emission
Materials used for thermionic emission are typically what type of material?