C) Right! To find out how this works, it is necessary to know how light comes into being (you do not need to read this if you already completed station 1, you can directly jump to the explanation of the fluorescence): Atoms compose itself of electrons (charged negative) and protons (charged positiv) in the nuclear. The electrons move on shells around the nuclear. The more the shell is external, the higher the energy of the electron is.

If energy is introduced, for example electricity or photons (light particle), the electron „jumps“ onto a higher shell. But it can do this only for short time. After some milliseconds it „jumps“ back and releases the absorbed energy in form of a photon.

Light diffuses as waves with a certain wavelength. The photon defines a part of such a wave. The shorter the wavelength is, the higher energy of the light.

The wavelength determines the colour of the light too. Light with a long wavelength is red, with a short one it is blue. All the other colours are inbetween this. White light composes itself from all those colours.

White light is for example sunlight.

When a material absorbes light, normally he doesn´t emitt it all. A material we can see as blue only reflects the blue light. He absorbs the rest and releases it as warmth.

Another example: White material reflects nearly all the light, so it releases nearly nothing as wamrth. Black material absorbs all the light. And the result you can feel: it is hotter than the white one.

Visible for us are wavelengths between 200nm and 800nm (1nm=0,000000001m).



But during the fluorecence the absorbed (taken) waves are longer (have less anergy) than the emitted (given) waves. This is because the electron doesn´t jump directly to his original shell. It jumps to a shell between his current shell and his original shell and emitts only a small amount of energy. When it jumps onto his original shell it emitts again only a small amount of energy.

Fluorescence comes into being under ultraviolett (blue) light. This is a light with a wavelength of 380nm to 100nm. We are not able to see this light.