Have you ever seen banknotes being checked in a shop? They are put into a box with a violet lamp. If they are real they glow with little ribbons and straps.

All these phenomena make use of ultraviolet light. The light of quartz lamps may burn your skin. 10% of the Sun light is ultraviolet. It's not much but still it is dangerous.

In Poland, 80% percent of holiday-makers are said to sunbathe so much that they risk developing skin cancer.

Ultraviolet lies within short wavelength band of the electromagnetic spectrum range. It is high-energy radiation compared to visible light and it has various practical applications.

Ultraviolet is widely used in superficial lighting - popular fluorescent lamp would emit ultraviolet if it were not for a white scintillation layer covering the lamp tubes form inside. The gas inside the tube emits ultraviolet, which in turn activates particles of scintillation layer. By choosing different kind of scintillation layer we can obtain different radiation colours. This phenomenon is called photoluminescence.

Many substances and organic dyes reveal photoluminescence properties when exposed to ultraviolet light. Minerals like fluoride (CaF2) and even Tonic Water, which contains compounds of quinine (see the photo) are examples. We utilise this phenomenon, by adding such dyes to the printing ink used for printing banknotes. The parts of banknotes printed with such printing ink radiate when placed in special banknote testers.

Solar light spectrum reaching the surface of the Earth would contain much more ultraviolet, if it were not absorbed by the atoms of oxygen and nitrogen (within the 'hardest' wavelength band of 150-250 nm) and by the ozone particles within the remaining 250 -350 nm band present in solar light spectrum. Ozone constitutes just a fraction. Under the 'regular' pressure at the ground level its layer would be only 3 mm thick. But it is extremely important for live beings safety.