electromagnetic Spectrum

electromagnetic Spectrum

1. Radiowaves

   • Radio waves have lower frequencies and longer wavelengths than microwaves. A radio programme receiver does not need to be directly in view of the transmitter to receive programme signals. For low frequency radio waves diffraction can allow them to be received behind hills, although repeater stations are often used to improve the quality of the signals.
     • They are used to transmit television and radio programmes. Television uses higher frequencies than radio.

2. microwaves

   • Microwave radiation has lower frequencies and longer wavelengths than visible light. Microwaves with certain wavelengths are absorbed by water molecules and can be used for cooking.
     • Microwave radiation can also be used to transmit signals such as mobile phone calls. Microwave transmitters and receivers on buildings and masts communicate with the mobile telephones in their range.

3. infrared

   • Infrared radiation is absorbed by the skin and we feel it as heat.
     • used in heaters, toasters and grills

4. visible light

5. ultra violet

   • Ultraviolet radiation is found naturally in sunlight. We cannot see or feel ultraviolet radiation, but our skin responds to it by turning darker. This happens in an attempt to reduce the amount of ultraviolet radiation that reaches deeper skin tissues. Darker skins absorb more ultraviolet light, so less ultraviolet radiation reaches the deeper tissues
     • used in: sun beds security pens fluorescent lights

6. x-rays

   • X-rays have a lower frequency than gamma radiation. Like gamma rays, they cannot be seen or felt. X-rays mostly pass through skin and soft tissue, but they do not easily pass through bone or metal.
     • X-rays are used to produce photographs of bones to check for damage such as fractures. They are also used in industry to check metal components and welds for cracks or other damage. Lower doses of X-rays can cause cells to become cancerous, so precautions are taken in hospitals to limit the dose received by patients and staff when X-ray photographs are taken

7. Gamma rays

   • Gamma waves have a very high frequency. Gamma radiation cannot be seen or felt. It mostly passes through skin and soft tissue, but some of it is absorbed by cells.
     • Uses: to sterilise surgical instruments to kill harmful bacteria in food to kill cancer cells ( that lower doses of gamma radiation could lead to cells becoming cancerous)