# When ultraviolet radiation is shone onto a zinc plate, electrons are emitted from the surface. Explain why the emitted electrons have a range of kinetic energies rather than all having the same kinetic energy.

> AQA A-Level Physics (7408) — 3.2.2 EM Radiation and Quantum Phenomena · Explain · 5 marks

## Mark scheme (5 marks)

1. Each photon transfers its energy to one electron (one-to-one interaction)
2. The energy used to remove an electron from the surface equals the work function
3. Electrons below the surface must do extra work to reach the surface / lose energy travelling through the metal
4. The remaining energy after escaping becomes the kinetic energy of the emitted electron
5. Electrons from different depths lose different amounts of energy, so they are emitted with different kinetic energies / maximum kinetic energy is for surface electrons

## Key terms

- [kinetic energy](https://www.gradenine.co.uk/glossary/kinetic-energy)

## Related

- [Revision notes for AQA A-Level Physics (7408)](https://www.gradenine.co.uk/learn)
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Source: [GradeNine](https://www.gradenine.co.uk/q/when-ultraviolet-radiation-is-shone-onto-f2a4eaba) · Published by Druglandscape Ltd.