Electromagnetic Waves

sanakaka2
Mind Map by sanakaka2, updated more than 1 year ago
sanakaka2
Created by sanakaka2 about 7 years ago
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GCSE Physics P1 (Electromagnetic Waves) Mind Map on Electromagnetic Waves, created by sanakaka2 on 05/06/2013.
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Electromagnetic Waves
1 Gamma rays and x-rays
1.1 X-rays pass through soft tissue but are absorbed by bone
1.1.1 X-rays produce radiographs
1.1.1.1 Gamma radiation is electromagnetic radiation from radioactive substances
1.1.1.1.1 Gamma rays can be used to kill harmful bacteria in food, sterilise surgical equipment and to kill cancer cells
2 Visible light and ultraviolet radiation
2.1 Light from the Sun and light bulbs is called white light, because it has all colours of the visible spectrum on it
2.1.1 Ultraviolet (UV) radiation makes some chemicals emit light
2.1.1.1 UV radiation is harmful to the human eye and can cause blindness
2.1.1.1.1 UV radiation comes from the Sun, and too much of it can cause skin cancer
3 Infra-red waves, microwaves and radio waves
3.1 All objects emit infra-red radiation
3.1.1 The hotter an object is the more radiation it emits
3.1.1.1 Infra-red radiation is absorbed by the skin, which kills skin cells as they heat up
3.1.1.1.1 Infra-red devices include heaters and remote controls
3.1.1.1.1.1 Microwaves are shorter than radio waves in wavelength, even though they come before radio waves in the electromagnetic spectrum. This is why they are called microwaves
3.1.1.1.1.1.1 We use microwaves for communication and heating food in microwave ovens
3.1.1.1.1.1.1.1 Radio waves are longer in wavelength than microwaves – but appear after microwaves in the electromagnetic spectrum because they have a lower frequency
3.1.1.1.1.1.1.1.1 We use radio waves to carry radio, TV and mobile phone signals
3.1.1.1.1.1.1.1.1.1 Radio waves are emitted from an aerial
3.1.1.1.1.1.1.1.1.1.1 Analogue and digital signals
4 The electromagnetic spectrum
4.1 The wavelength of a wave is the distance from one wave peak to the next wave peak along the waves
4.1.1 The frequency is the number of complete waves passing a point per second
4.1.1.1 We measure frequency in the unit of hertz (Hz) when:
4.1.1.1.1 - 1 Hz = 1 complete wave per second
4.1.1.1.1.1 - 1 Hz = 1 complete wave per second
4.1.1.1.1.1.1 - 1 kilohertz (kHz) = 1000 Hz
4.1.1.1.1.1.1.1 - 1 megahertz (MHz) = 1,000,000 Hz
4.1.2 The speed of a wave is worked out by using: wave speed (m/s) = frequency (Hz) x wavelength (m)
4.2 Alternatively, the frequency can be worked out by using:
4.2.1 frequency = wave speed (in m/s) ________________________________ wavelength (in metres)
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