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Radio waves have wavelengths ranging up to the length of 1000 American football fields lined up one after the other.
Describe the role of electromagnetic waves in:
– radio and television communications (radio waves) RUH
– satellite television and telephones (microwaves) _EAMON
– electrical appliances, remote controllers for televisions and intruder alarms (infrared) SAM
– medicine and security (Xrays) EMILE
Demonstrate an awareness of safety issues regarding the use of microwaves and Xrays
In 1873, James Clerk Maxwell published a book in which he speculated the idea that electricity and magnetism were combined into one force rather than two, which had been the previous belief.
And there you have it.
Electricity and magnetism: electromagnetism.
Humans wanted to this force for themselves and eventually found ways of harnessing some of the many powers of the electromagnetic spectrum.
Here are some (fairly simple) explanations of these "powers".
Infrared radiation is used in
electrical heating.
The sound is transformed into waves to travel.
These waves all have different frequencies.
A radio has an antenna.
The antenna will pick up these different waves (radio signals).
A tuner can be tuned to a certain frequency so that the radio antenna only picks up the waves with that specific frequency.
The waves are transformed back into sound.
Then you hear the sound.
In telecommunication, we now sometimes use telecommunication satellites.
Waves are sent to satellites (by antennas), again at different frequencies to distinguish them.
The satellites then either send them back to earth with reflectors to have a single, precise beam.
This means that if the antennas on the ground aren't properly lined in place, the entire signal could be lost
Another type of transmission is called in-band. This allows for the digital signals to be carried by normal AM or FM radio waves.
We say that the information "piggy-backs" on the other transmission.
Infrared sensors & Alarms
These sensors work by detecting
a rapid change in infrared wavelength.
Thermography
The human body emits a 9-10 micro millimeter wavelength from our body heat.
So when person moves, the sensor detects the movement of waves and goes off.
The Binary Codes
http://www.darvill.clara.net/emag/emagmicro.htm
http://imagine.gsfc.nasa.gov/docs/science/know_l1 emspectrum.html
http://i00.i.aliimg.com/photo/v0/140793352/Far_Infrared_Heating_Panel.jpg
http://en.wikipedia.org/wiki/Infrared#Communications
http://electronics.howstuffworks.com/remote-control2.htm
http://home.howstuffworks.com/home-improvement/household-safety/security/question238.htm
http://en.wikipedia.org/wiki/Radio_wave#Radio_communication
http://science.hq.nasa.gov/kids/imagers/ems/radio.html
http://www.cnes.fr/web/CNES-en/1109-how-telecommunications-satellites-work.php
http://en.wikipedia.org/wiki/X-ray#Medical_uses
http://science.howstuffworks.com/transport/flight/modern/airport-security4.htm
http://en.wikipedia.org/wiki/X-ray_generator
Button 1 = 000 0000
Button 2 = 000 0001
Button 3 = 000 0010
Button 4 = 000 0011
Channel Up = 001 0001
Channel Down = 001 0001
Power On = 001 0101
Power Off = 010 1111
Volume Up = 001 0010
Volume Down = 001 0011
X- Rays are used in airport security to detect items in luggage and classify things in three categories:
In the medical field X-rays are used in a similar way as in security but to detect things like bone fractures. Bones contain lots of calcium which absorbs X-rays very well and thus less rays reach the detector so that we can create a very clear image of the bones.
TV Remotes
The rays are emitted, pass through the object and then are read by a detector
X-Rays can also detect things like lung cancer, pneumonia, and kidney stones
When the button is pressed, the circuit sends the binary command with infrared waves to the TV
X-Rays are less useful for imaging of very sift tissue such as brain or muscle tissue
X-Rays contain a lot of energy and therefore they can pass through a lot of things. Different things absorb different amounts of the rays and when the rays reach the energy detector the amount of energy that reaches the detector is used to create an image of items in a bag.
X-ray of an arm, showing very clear damage to the bones
When the Waves reach the TV,
There is a sensor which converts the infrared waves into electrical signals.
The prefix-The wavelength of microwaves range from 1mm to 1m.