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Electromagnetic Waves

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by

Beth Arrowsmith

on 26 April 2013

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Transcript of Electromagnetic Waves

Beth Arrowsmith Electromagnetic Spectrum Radio Waves Frequency is 10 Hz Microwaves Infra-red Visible Light Ultra-violet X-rays Gamma Rays 4 Frequency is 10 Hz 8 Wavelength is 10 m 3 Commonly used for television and communications (e.g. mobile phones, police radios) Large amounts of radio waves are believed to cause cancer, Leukaemia and other disorders Wavelength is 10 m -2 Microwaves are used for cooking and communications (transmit signals for mobile phones) Being exposed to a large amount of microwave radiation can cause the internal body tissue to heat up and so the cells could be burnt
or killed Frequency is 10 Hz 12 Wavelength is 10 m -5 Infra-red is used in specialized infra-red cameras, toasters, grills, remote controls and it is used for optical fibre communication Optical Fibres Optical fibres are used to carry data quickly across long distances. They do this by using Total Internal Reflection Infra-red can cause skin burns Frequency is 10 Hz 15 Wavelength is 0.5 x 10 m -6 Visible light is used for seeing things, communication and is also used for photography Very intense light can damage the retina at the back of the eye Frequency is 10 Hz 16 Wavelength is 10 m -8 Frequency is 10 Hz 18 Wavelength is 10 m -10 Frequency is 10 Hz 20 Wavelength is 10 m -12 Ultra-violet light is used for detecting forged bank notes (by fluorescence), sun beds and security pens Ultra-violet light is found naturally in sunlight We cannot see or feel Ultra-violet radiation, however our skin responds by turning darker. The reason for this is because our body is trying to reduce the amount of radiation that reaches our deeper skin tissues. People with darker skin absorb more ultra-violet light, so less radiation gets to the deeper tissues.
This process is very important because ultra-violet radiation can cause some of the normal cells to become cancerous. Ultra-Violet Radiation Dangers of Ultra-Violet Light Ultra-violet waves can cause skin cancer by ionizing the cells under the surface of the skin. 12 -5 Microwaves 12 -5 Microwaves Infra-Red Frequency is 10 Hz 12 Wavelength is 10 m -5 Types of UV
Radiation UV A UV B UV C Low
frequency severe sunburns
damages
cells Medium
frequency High
frequency severe damage
to
cells weaker effects
than UV
B There are 3 different types of UV radiation and they are each dangerous on their own level X-rays are used for looking at bones in the body If it is absorbed by cells, it can cause cancer because ionization can occur X-rays are fired through your body and into a film behind. When the film is developed, you can see a clear image of the bone. This is because the x-rays go go through the flesh but not the bone! How X-rays Work? Gamma rays can be used to kill cancerous cells(chemography) and can also be used to kill bacteria in food and sterilize surgical equipment As well as curing cancer, if a lower dose of gamma radiation is absorbed it can cause cancer Visible Light Communication Ships use visible light to communicate through semaphores. Semaphores are basically big flashlights that people turn on and off in a specifically coded pattern. Radio Waves Communication Television uses a higher frequency than radio
Radio waves use diffraction to receive low-frequency waves and they can be heard behind hills
The lowest frequency of radio waves are reflected from an electrically charged layer in the upper part of the atmosphere, which is called the ionosphere.
This means that signals can be received, even if the person is not in view Microwave Communication Microwaves have transmitters and receivers on top of buildings and these masts communicate with any mobiles that are in their range
Microwaves that are used in mobile phones are not a health risk because the microwaves are not intense enough and so they won't damage the internal tissues
Some microwave radiation wavelengths go through the Earth's atmosphere and can be used to transmit information to and from satellites that are in orbit.
Microwaves are also used for satellite television signals
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