---
tags:
  - quantum
---
$$E=hf$$
## Photoelectric Effect

- Emission of charged particles when exposed to UV light
- Electrons
- Einstein suggested light is quantised

1. The maximum KE of ejected electrons is independent of intensity, but dependent on frequency $n$
2. There is a minimum frequency n0below which there is no emission
3. No time delay (less than 1 ns) before the onset of emission –but the rate of electrons depends on the intensity.

![photo-electric](img/photo-electric.png)
![fermi-vacuum-level](img/fermi-vacuum-level.png)

![em-spectrum](img/em-spectrum.png)
-   Radio spectrum
	-   30Hz – 300 GHz