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P12 - Electromagnetic waves - Coggle Diagram
P12 - Electromagnetic waves
Electromagnetic spectrum
Electromagnetic waves transfer energy from a source to an absorber.
The wave speed equation is used to calculate the frequency or wavelength of electromagnetic waves.
The human eye can only detect visible light. The wavelength of visible light ranges from about 350nm to 650nm
Wave speed
v = f x A
v = wave speed
f = frequency, hertz, Hz
A = wavelength, m
The electromagnetic spectrum
Radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays
Light, infrared, microwaves and radio waves
Radio waves are used for radio and TV broadcasting, radio communications and mobile phone calls.
Mobile phone radiation is microwave radiation and also radio waves at near-microwave frequencies.
Microwaves are used to carry satellite TV programmes and mobile phone calls
Hazardous - Microwaves and radio waves can heat the internal parts of peoples body's. Infrared radiation can cause skin burns
Infrared radiation is used for carrying signals from remote control headsets and inside optical fibres.
White light contains all the colours of the visible spectrum.
Communications
More research is needed to evaluate whether or not mobile phones are safe to use.
Optical fibers are very thin, transparent fibers that are used to transmit communication signals by light and infrared radiation.
Microwaves are used for satellite TV signals.
Radio wave of different frequencies are used for different purposes because the wavelength of waves affects; travel length, spread, amount of information carried.
Ultraviolet waves, X-rays & gamma rays
Gamma rays are used to kill harmful bacteria in food, sterilise surgical equipment, and to kill cancer cells.
Ionising radiation makes uncharged atoms become charged.
X-rays are used in hospitals to make X-ray images.
X-rays and gamma rays damage living tissues when they pass through it.
Ultraviolet waves have a shorter wavelength than visible light and can harm the skin and eyes.
X-rays in medicine
X-rays are ionising radiation and so can damage living tissue when they pass through it.
X-rays are absorbed more by bones and teeth than soft tissues.
X-rays are used in hospitals to make images of internal body parts and destroy tumors at or near body surface.