Virtual Lab - Photoelectric Effect
The photoelectric effect is all about kicking electrons out of metals, using light.
When the light strikes the metal, its energy is transferred to the electrons. Different wavelengths (or colours) of light carry different amounts energy. If the light has a high enough energy, the electrons will escape from the surface of the material. If the energy of the light is too low, then it will not. Thus there is a threshold of energy needed for the metal to lose an electron, and this threshold is different for different materials.
To investigate this phenomena, you will be using the following pieces of equipment:
Light sources: a set of six LED’s (light emitting diodes) of various colours, with known wavelengths. The wavelength can be used to calculate the energy carried by the light.
Electron emitter: this is the metal target, a photocathode that emits electrons when hit light of high enough energy.
Electron collector: a capacitor, which will collect the electrons ejected from the photocathode.
When we shine light on the metal (photocathode), we need some way of detecting when electrons are emitted. In this experiment, a nearby capacitor is used to collect the electrons. The build up of charge causes an increase in the voltage across the capacitor. Thus, the capacitor voltage is related to the emission of electrons by the photocathod.