Fibre optic cables use visible light to transmit data

• Optical fibres are thin glass or plastic fibres that can carry data over long distances as pulses of visible light

• They work because of reflection, the light rays are bounced back and forth until they reach the end of the fibre

• Visible light is used in optical fibres

• Light is not easily absorbed or scattered as it travels along a fibre

Ultraviolet radiation gives you a suntan

• Fluorescence is a property of certain chemicals, where ultra-violet radiation is absorbed and then visible light is emitted. That’s why fluorescent colours look so bright-they actually emit light

• Fluorescent lights generate UV radiation, which is absorbed and re-emitted as visible light by a layer of a compound called a phosphor on the inside of the bulb. They’re energy-efficient so they’re good to use when light is needed for long periods

• Security pens can be used to mark property with you name, under UV light the ink will glow, but it’s invisible otherwise. This can he,p the police identify your property if stolen

• Ultraviolet radiation is produced by the sun, and exposure to it is what gives people a suntan

• When it’s not sunny, some people go to tanning salons where UV lamps are used to give them an artificial suntan. However, overexposure to UV radiation can be dangerous

X-rays and gamma rays are used in medicine

• Radiographers in hospitals take X-ray photographs of people to see if they have any broken bones

• X-rays pass easily through flesh but no so easily through denser material like bones or metal. So it’s the amount of radiation that’s absorbed that gives you an X-ray image

• Radiographers use X-rays and gamma rays to treat people with cancer. This is because high doses of these rays kill all living cells-so they are carefully directed towards cancer cells, to avoid killing too many normal healthy cells.

• Gamma radiation can also be used as a medical tracer-this is where a gamma-emitting source is injected into the patient, and its progress is followed around the body. Gamma radiation is well suited to this because it can pass out through the body to be detected

• Both X-rays and gamma rays can be harmful to people so radiographers wear lead aprons and stand behind a lead screen or leave the room to keep their exposure to them to a minimum