Electromagnetic Waves

• Uses and Risks of Gamma Rays


  Uses: Medical imaging and therapy, astronomy, sterilisation and food preservation.

  Risks: Gamma rays are extremely penetrating and damaging to living tissues and cells.

  Why they're used: Since gamma rays are extremely ionising, they can be used to kill bacteria or tumour cells
• Uses and Risks of X-rays

  Uses: Low-energy X-rays are used for medical and industrial imaging while high-energy X-rays are used to treat cancer. X-rays are also used for security purposes to detect weapons in airports (and other places).

  Risks: X-rays are highly ionising even in low doses so, exposure to X-rays should always be kept to a minimum. People who work with X-rays will place metals like lead to shield themselves.

  Why they're used: X-rays penetrate soft materials (like body tissue). Bones are dense materials that absorb X-rays. X-rays can build a shaded image of bones and body tissue.
• Uses and Risks of Ultraviolet Light

  Uses: Ultraviolet light is used in medical and forensic photography, air purification, disinfection, tanning and medical therapy. It can also be used to detect fake bank notes.

  Risks: Exposure to too much ultraviolet light can cause skin burns, skin cancer and cataracts(protein clump obstructs the lens, making your vision worse)

  Why they're used: In lamps, UV photons excite (give energy to) atoms. The atoms then release visible light. In sun tanning, UV excites (gives energy to) skin cells. The skin cells then change colour.
• Uses and Risks of Infra-red Radiation

  Uses: Infra-red radiation is used in TV controls. Infra-red can also be used for security purposes, such as in intruder alarms by detecting body heat.

  Risks: Infra-red radiation can cause serious skin burns if emitted from high-intensity sources.

  Why it's used: In an IR remote control, light is used to carry signals between the remote control and the device it's directing. Infra-red cameras can detect a range of frequencies. These frequencies can be shown in different colours to depict images.
• Uses and Risks of Microwaves

  Uses: Microwaves are used for satellite communications (transmitting signals between stations on Earth and satellites). Microwaves are also used to transmit signals from a nearby phone mast to a mobile phone. Microwaves are also used to heat food.

  Risks: Humans are largely made up of water so, exposure to microwaves could have a harmful effect. This is why exposure to microwaves should always be reduced. People should always shield themselves. An example of this is the protective layer on microwaves.
• Why Microwaves are used:

  Why they're used: Microwaves have a high enough frequency to penetrate the Earth’s atmosphere and reach satellites. Microwaves travel in straight lines through the atmosphere. This makes them good for transmitting signals. Microwaves are absorbed by water, heating the water in the process. This makes microwaves useful for cooking food because food contains lots of water.
• Uses and Risks of Radio Waves

  Uses: Radio waves are used for radio and TV communications.

  Risks: At high intensities, radio waves can cause internal heating of living tissue with potentially harmful effects.

  Why they're used: Since radio waves have long wavelengths, they can be transmitted (sent) around the Earth’s surface and buildings without interference.
• Uses of Visible Light

  Uses: We use visible light to see the world around us and in fibre optics.

  Why it's used: We use visible light in optical fibres because it can be totally internally reflected. This means that we can transmit signals (information) along optical fibres without the signals (information) getting lost.