who are the electromagnetic waves in cell phones?
101320
The electromagnetic waves used by cell phones are called radio waves. Waves are characterized by their frequency; that is, the number of times that the wave pattern repeats in a second (or some other time interval). For example, the radio waves that a type of cell phone called a GSM phone use are in frequency bands centered on 850 MHz, 900 MHz, 1800 MHZ and 1900 MHz. That is, the radio waves that a GSM cell phone using the 850 MHz band oscillate roughly 850 million times every second (the pattern repeats 850 million times every second). \n\nThe radio waves that travel back and forth from the cell phone tower to your cell phone are electromagnetic. Your voice signal on the cell phone is carried by modulating electromagnetic waves. No electromagnetic waves, no signal, and therefore, no cell phone.  Without electromagnetic waves, there would be no radio, no tv and no cell phones, and no cordless phones, and no wireless PCs etc etc.\n\nAll light is electromagnetic waves. All heat is electromagnetic waves. Electricity is actually an electromagnetic wave travelling in a wire (the electrons move much slower than this wave). So without electromagnetic waves, the universe would be a very different place.
902185
the radio/stereo, television, phone, cameras, electricity
471190
Electromagnetic radiation in the 1 to 1000 m wavelength range.
715907
Electromagnetic waves don't need medium to travel.\n\nLike light, radio too, is an elctromagnetic wave, so it can travel through vacuum.
968111
Please re-submit your question explaining what medium the waves propagate in.\nDoes ELF refer to Extra Low Frequency radio waves in your question?
75752
Interesting question.  Any electromagnetic wave moves at the speed of light (following tradition use the symbol c), and since nothing can move faster than c (nothing carrying information anyway) the waves from a cellphone on a moving train would all be moving away from the user at the speed c.\n\nHowever, this does not mean that the train would need to be moving at the speed of light in order to render a cellphone useless.  The doppler effect still applies (though the formulas for relativistic doppler shifts are different than those of sound).  Since the train is moving, we'll call the person using the phone on the train a source.  All one would need to answer the question is what frequency the source emits and what band of frequencies that the detector can use.  When the train is moving at such a speed as to shift the frequency of the source out of a detectable range (e.g. when it's moving toward the detector the frequency will be too high, or away, too low), the cellphone will not work.  One thing to mention, although the train will not need to be moving AT the speed of light, it will probably need to be moving faster than any of the trains you or anyone else has seen!
977478
There have been many studies into Radio Frequency (RF) absorption into tissue and whether or not it causes damage.  Cellphones are the biggest target, because they contain a radio transmitter which you hold on or near your head.  The FCC uses a test called SAR (specific absorption rate) to measure radiation absorbtion rates into tissue.    The Wiki entry for SAR:\n\n"SAR is a measure of the rate at which radio frequency (RF) energy is absorbed by the body when exposed to radio-frequency electromagnetic field. The most common use is in relation to cellular telephones. In the United States, the Federal Communications Commission (FCC) has adopted limits for safe exposure to RF energy produced by mobile devices and requires that phones sold in the U.S. have a SAR level at or below 1.6 watts per kilogram (W/kg) taken over a volume of 1 gram of tissue. In the EU the corresponding limit is 2 W/kg taken over a volume of 10 grams."\n\nBluetooth devices, by their very nature, are short-distance radio communication devices, and so will operate at a far lower radio emission level than their cellular cousins.  A study by William G. Scanlon of Queen's University in Belfast found that a typical Ericsson Bluetooth radio module generates a SAR of just 0.001 watts per kilogram, which is well within the safe limits.
197446
I've heard it could cause health problems because of the electromagnetic energy. Doctors are also concerned because so many kids are using cell phones now. I only use mine when I have to. I really do hate them.
362672
Radiowaves, look it up.\nAnd you definately got the category wrong.
925755
Microwave is the back bone of many of the distant multiple telephone svc. the wide band satellite service is the link to tie the world together. Tv & telephone service. The radiation doecnt cause any real health problems as the beams are very direct as a beam of light. It is a lot of our world communications.
107520
There are many types of electromagnetic radiation. Some we can see, which we call light. Some is lower frequency, like infrared radiation, which is the heat we feel from sunlight, or from a campfire or a stove. Some is higher frequency , like ultraviolet radiation, the radiation. Electromagnetic radiation can travel through space. It does not need any propagation medium to travel in.
732764
Are they cell phones?
438842
Like light rays radio waves are reflected refracted and diffracted and absorbed by materials. At certain angle of reflection radio waves are also polarized.\n\nSince it is an E.M wave it travels in vacuum or air with velocity C.\n\nThey are reflected by metals, but absorbed by many substances like wall. The absorption depends upon the thickness of the material.Usually the thicknes of a wall is such as to absorb radio waves. \n\nBecause of long wavelength it can bend across obstacles, and even small cleavage in a wall can fill a room with radio waves.
30942
If it'smade from iron materials the electromagnetic wave will be absorbed by the iron and the signale in teh phone will be so bad
509957
Electromagnetic radiations or waves are propagating in space. Electromagnetic waves have electric and magnetic components, the electric field and the magnetic field oscillate at right angles to each other and to the direction of propagation.\nAs any other waves e.m. waves are characterized with  frequency (number of vibrations in one second), wavelenght (the distance from one crest to the next crest in the sinus wave) and radiant energy. \nThe range of the e.m. waves is called the electromagnetic spectrum. The highest frecvency and energy / the lowest wavelenght e.m. radiations are gamma rays (are shorter than the size of the nucleus in the atom) then X rays, ultraviolet radiations, visible light, infrared radiation (heat radiation), microwaves, and radiowaves which has the lowest frequency and longest wavelenght (can be several km long). We can see only the visible light, the other e.m. radiations are invisible to us. But they can have an effect on our organism. They have a lot of technical, medical and other use.\n\nfor more see >>\nhttp://en.wikipedia.org/wiki/Electromagnetic_radiation
940858
The radio waves currently used for telecommunication or broadcasting are electromagnetic waves (non-ionizing radiation) which do not have enough energy to ionize atoms from materials. Although some of the electromagnetic waves, such as ionizing radiation including X-ray or gamma-ray, have high frequencies and strong energy that ionize atoms, they are very different from the radio waves we are dealing with; that is non-ionizing radiation.
253932
Electromagnetic radiation is a propagating wave in space with electric and magnetic components. These components oscillate at right angles to each other and to the direction of propagation.\n\nThe term electromagnetic radiation is also used as a synonym for electromagnetic waves in general, even if they are not radiating or travelling in free space. This sense includes, for example, light travelling through an optical fiber, or electrical energy travelling within a coaxial cable.\n\nElectromagnetic (EM) radiation carries energy and momentum which may be imparted when it interacts with matter.