# A student investigates the photoelectric effect using two different metals, P and Q. Metal P has a higher work function than metal Q. The student shines light of the same frequency onto both metals. Describe and explain the differences in the photoelectric emission from the two metals.

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

> Two metals, P and Q, are used in a photoelectric effect investigation. Metal P has a higher work function than metal Q. Light of the same frequency is shone onto each metal in turn.

## Mark scheme (5 marks)

1. Electrons are only emitted from the metal whose work function is less than or equal to the energy of the photon
2. Metal Q (lower work function) will emit electrons / is more likely to emit electrons from the given light
3. Each photon gives all of its energy to one electron
4. The maximum kinetic energy of emitted electrons from Q is greater than it would be from P (if P emits at all), because less energy is used to overcome the work function
5. The number of electrons emitted per second (from the same metal) does not depend on the work function but on the number of photons / intensity of the light

## Key terms

- [work function](https://www.gradenine.co.uk/glossary/work-function)
- [photoelectric effect](https://www.gradenine.co.uk/glossary/photoelectric-effect)
- [emission](https://www.gradenine.co.uk/glossary/emission)

## Related

- [Revision notes for AQA A-Level Physics (7408)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-investigates-the-photoelectric-effect-0ea23dc8) · Published by Druglandscape Ltd.