Physics

3.6 - UV Light

6 min

Visible light

Suntans and fluorescence

Security and sterilisingOutside your course

note 1 of 2

Fluorescence and fluorescent lamps

Fluorescence is a property of certain chemicals: they absorb ultraviolet (UV) radiation and then emit visible light.

How a fluorescent lamp works

The lamp generates UV radiation inside the tube.
A layer of phosphor coats the inside of the glass. It absorbs the UV and re-emits it as visible light.
Fluorescent lamps are energy-efficient, so they suit places needing light for long periods, such as classrooms, offices, and hospitals.

A glass tube of argon gas and mercury vapour, with electrons flowing from the cathode to mercury atoms that give out ultraviolet radiation, and the phosphor coating giving out visible light.

note 2 of 2

Dangers of ultraviolet radiation

UV damages the surface cells of the skin and can cause premature ageing.
Some UV is ionising - it carries enough energy to knock electrons off atoms.
- This can disrupt the DNA in skin cells, causing mutation and leading to skin cancer.
UV can also harm the eyes, causing eye conditions and even blindness.

Reducing the risk

Wear sunscreen with UV filters in strong sunlight.
Limit the time spent in strong sunlight.

The Sun sends purple arrows of UV onto a blue figure covered in pink lumps, labelled UV radiation and cell mutation & destruction, beside a close-up of a half-wrinkled face labelled premature aging.

key terms

TermDefinition

FluorescenceA property of certain chemicals where they absorb ultraviolet radiation and emit visible light.

Ionising radiationRadiation that has enough energy to knock electrons out of atoms, turning them into ions.

end of notes

Key points to remember

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3.7 - X-Rays & Gamma RaysNext up