Radio waves

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What are they?
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 Hz, and corresponding wavelengths ranging from 1 millimeter to 100 kilometers. They are transverse.

Are they dangerous?
It is believed that exposure to large doses of radio waves can result in disorders such as cancer. There are also claims that people who are exposed to the low frequency field that are caused by overhead cables are affected.

Where do they come from?
Naturally occurring radio waves are made by lightning, or by astronomical objects.
Manmade radio waves are generated by a transmitter.

How do we detect them?
Radio waves are detected by the use of radio telescopes.

What can they be used for?
Manmade radio waves have been used for a long time to send information, receive information, and to 'see' objects. Radar uses radio waves to 'see' distant objects by bouncing waves off an object and seeing how long it takes for the waves to return. Radar can even be used to find oil or see what chemicals are in soil. Radios also use these waves to send and receive information.

Natural radio waves were first discovered in the 1930s by Karl Guthe Jansky, working for Bell Laboratories. Before his discovery, everyone thought only people could generate radio waves. Bell was detecting static on his radio channels, and had Jansky try to figure out where this static, or interference was coming from. Surprisingly, the interference was coming from space! This discovery eventually led astronomers to look at radio waves along with optical waves to find things in the sky. These radio astronomers use giant Radio telescopes, shaped like satellite dishes, to gather and analyze the waves.

Radio waves are used for many things today. They broadcast radio and television, communicate with satellites, let mobile phones communicate with each other, make radar systems, and allow computers to share information without wires.
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X-rays

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What are they?
X-rays are electromagnetic waves of high energy and very short wavelength (between ultraviolet light and gamma rays), which are able to pass through many materials opaque to light.

Are they dangerous?
Even low 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.


Where do they come from?
X-rays are generated by an X-ray tube, a vacuum tube that uses a high voltage to accelerate the electrons released by a hot cathode to a high velocity. They are produced in parcels of energy called photons.

How do we detect them?
X-ray detectors vary in shape and function depending on their purpose. Imaging detectors such as those used for radiography were originally based on photographic plates and later photographic film but are now mostly replaced by various digital detector types such as image plates or flat panel detectors. For radiation protection direct exposure hazard is often evaluated using ionization chambers, while dosimeters are used to measure the radiation dose a person has been exposed to. X-ray spectra can be measured either by energy dispersive or wavelength dispersive spectrometers.


What can they be used for?
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 shadow 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, and can detect objects hidden in the luggage of aircraft passengers.


In the table below, fill the cells with very brief notes. Use the other pages to gather the information from, and you may want to go outside of this wiki if you really can't find the information here (though I'd be surprised!).



Gamma
X-rays
UV
visible
IR
microwaves
radio
How are they generated?
Natural radioactive decay, nuclear explosions and lightning in thunderstorms.
X-rays are created when a photon strikes a metal target.
They come from the sun, but you can get man made lamps.
By luminous objects. E.g. the sun, light bulbs etc.
Infrared waves are produced when light is exposed to heat or generated from heat.
Microwaves are emitted from a number of sources, for instance, in a mobile phone, they are generated by a transmitter chip and an antenna, while in a microwave oven they are generated by a 'magnetron'. They are also released as a form of electromagnetic radiation from large stars.
Naturally occurring radio waves are made by lightning, or by astronomical objects.Manmade radio waves are generated by a transmitter.
How are they detected?
Gamma-ray detectors typically contain densely packed crystal blocks. As gamma rays pass through, they collide with electrons in the crystal. This process is called Compton scattering, when a gamma ray strikes an electron and loses energy. These collisions create charged particles that can be detected by the sensor.
X-rays can be detected with a special piece of equipment called an x-ray detector.
To detect them you can simply use a filtrate this is the cheepest option and used frequently. As well as this you could use a UV dectector, they come in a range of styles and prices. The more you pay the better the quality.
Our eyes, cameras
Our eyes cannot see infrared waves but instruments that can sense infrared energy — such as night-vision goggles or infrared cameras–allow us to "see" the infrared waves emitting from warm objects such as humans and animals.
If the waves are used for communications we use a reciver to detect them. If we are checking for contamination we can use a gieger tube to test for them.
Radio waves are detected by the use of radio telescopes.
How might they be dangerous?
Gamma rays are radioactive.
When they pass through the human body they damage cells, most of which die, but some of the damaged cells mutate and divide faster, this is the start of cancer.
It can be dangerous as they damage and kill cells. When this happens to us we call it sun burn. It happens when our skin has seen a lot of sun or due to a lack of sun cream, and the skin starts to redden, it can be sore, but more often than not calms down; leaving darker, or more tanned skin. But many of the cells have been killed in the skin, for the minority this could result in cancer.
They can blind us
Infrared waves are heat waves. If the cells absorb too much infrared radiation the heating will damage or kill the cells.
Prolonged exposure to microwaves is known to cause cataracts, which is a clouding of the lens, in your eyes preventing you from seeing clearly. Recent research indicates that microwaves from mobile phones can affect parts of your brain - after all, you're holding the transmitter right by your head. Although there is a feeling that you're more vulnerable if you're young and your brain is still growing.
It is believed that exposure to large doses of radio waves can result in disorders such as cancer. There are also claims that people who are exposed to the low frequency field that are caused by overhead cables are affected.
What are the main or most significant uses?
Gamma rays can be used to kill cells, such as cancerous cells.
X-rays can be used to treat cancer, take medical images (such as skeletal x-ray scans), and pictures of far flung stars and planets via x-ray telescopes.
Ultra violet rays can be used for tanning, in a tanning bed or by the sun. Many people have suffered great damage from this and some have even developed cancer. They can also kill microbes.
To light things up.
-Night vision goggles pick up the infrared light emitted by our skin and objects with heat.-A remote control uses light waves just beyond the visible spectrum of light—to change channels on your TV.
-Infrared is also used for cooking in grills and toasters.
Microwaves cause water and fat molecules to vibrate, which makes the substances hot. Therefore we can use microwaves to cook many types of food. Mobile phones use microwaves, as they can be generated by a small antenna, which means that the phone doesn't need to be very big. The drawback is that, being small, they can't put out much power, and they also need a line of sight to the transmitter. Microwaves are also used by fixed traffic speed cameras, and for radar, which is used by aircraft, ships and weather forcasters. The most common type of radar works by sending out bursts of microwaves, detecting the "echoes" coming back from the objects they hit (like a bat uses echo location), and using the time it takes for the echoes to come back to work out how far away the object is. They are also used to transmit data over long distances with satelites.
Manmade radio waves have been used for a long time to send information, receive information, and to 'see' objects. Radar uses radio waves to 'see' distant objects by bouncing waves off an object and seeing how long it takes for the waves to return. Radar can even be used to find oil or see what chemicals are in soil. Radios also use these waves to send and receive information.Radio waves are used for many things today. They broadcast radio and television, communicate with satellites, let mobile phones communicate with each other, make radar systems, and allow computers to share information without wires.

Another good piece of work. You put a lot of energy into this and it shows. Good content and formatting. The images may need explaining or having captions.
The table is good, but rather over-full of data, as it needs to be memorisable!

Good work.

A- merit

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