What is electromagnetic radiation?

Answer 1

Electromagnetic waves are the mechanism by which electromagnetic energy (electromagnetic radiation) moves. They are composed of two components: an electric wave, or an electric field, and a magnetic wave or magnetic field. The fields are in dynamic motion, and these two waves are in phase and move at 90 degrees to each other. The orientation of this "package" can vary in the space through which it moves, which leads to what we term polarization, but the electric and magnetic components always maintain the right angle relationship to each other. Draw an "X" with the angles it creates equal to 90 degrees. Got it? A cross? Now rotate it just a bit. The whole thing. Now a bit more. Now a bit more. You are looking at the electromagnetic wave as it's coming at you (or going away), and you're changing the polarization of the cross without changing the cross itself. Let's jump.

One of the four basic forces in the universe is the electromagnetic force. Not the electric force, not the magnetic force, but the electromagnetic force. You can't have one without the other. Ever. A magnetic field is always created by some sort of charge movement. It is the only way a magnetic field can be created. Just like you can't have gravity without mass, you can't have magnetism without some sort of charge movement. Any time a charge moves, a magnetic field is created. All the time. Every time. No exceptions. Let's jump to go a step further.

Let's take a simplified example. Picture a pond as smooth as glass. We walk out on a low dock and kneel down at the water. Then we take our index finger and just "tap" the surface of the water one time. A ripple is generated, and it moves out away from the point where we initiated it. We good? Let's bounce a bit. If we take a charged particle like, say, an electron that is in orbit around an atom, and we give it some energy to kick it out to the next higher orbital; we have ionized the atom. The electron will then "dump" that extra energy and return to its original orbital. That energy it dumps will take the form of a "particle" or "package" of energy - a quantum of energy. And it is a moving electric and a complimentary moving magnetic field - just like the ripple on the pond. Only it is this "coupled" electric and magnetic "bundle" of energy. It's a photon, or a quantum of electromagnetic energy.

The energy of the wave is carried in the moving fields, and that is why the wave does not require a medium through which to travel. In fact, anything other than a vacuum will attenuate or "suck energy" out of the wave a bit at a time through the distance through which the wave travels in that medium.

As you might have guessed, electromagnetic radiation comes in different "amounts" or amplitudes, and in different frequencies (energies). From radio waves through microwaves, and through infrared light, visible light, ultraviolet light and X-rays all the way to gamma rays, there is a full spectrum of this energy.

This gets deep, but the essence of what is happening is here. Simple, but subtle and elegant. Reachable by even elementary school investigators. It is the essential nature of the universe we live in.

Wikipedia has more information, and a link is provided below to their post on electromagnetic radiation. Further investigation is encouraged. At least surf on over and look at the drawing of the moving and electric and magnetic fields to lock that in. Maybe skim the article while you're there, or at least bookmark it. You've just peeked through the window in the quantum mechanical universe. Enjoy the view. Wonder at it. It is the reality in which we live.

Answer 2

a wave produced by the acceleration of an electric charge and propagated by the periodic variation of intensities of, usually, perpendicular electric and magnetic fields.

While the above is the long used formal definition, a more useful contemporary explanation will include that EM waves are emissions by oscillators, at frequencies in wavebands similar to musical octaves (of which visible light is one) from longer than radio waves up to very short high energy gamma waves.

Propagation in a medium is via atomic scattering (particle charge and re-emission), the main 'directional' part being from ions, including free electrons (plasma) and termed 'coherent forward scattering'.

More complex molecular gasses also scatter sideways, giving us visible evidence of the passing of the charging waves.

Answer 3

Electromagnetic radiation, or EMR, is a term we apply to the phenomenon of the movement of electromagnetic (EM) energy through the propagation of a wave. This wave, which moves at the speed of light in a vacuum, is composed to two intertwined waves. (Light itself is an electromagnetic wave.) An electric and a magnetic wave that are in phase, but are perpendicular to each other, are self-propagating in this almost omnipresent, natural occurrence The wave has the properties of frequency (and wavelength, which is the inverse of frequency), and amplitude. It is also polarized, meaning it has polarity, owing to the orientation of the two constituent waves about their path of travel. We know something about this phenomenon because we have experienced it all our lives, at least in its form as light. Electromagnetic radiation is also given other names, depending on its frequency. The lowest frequency EM waves are radio waves, and they reach up into microwaves The microwaves, in turn, reach up into the far infrared (IR) band, then the near IR band. These are just below the optical frequencies, or the spectrum of visible light. We see red, orange, yellow, green, blue and violet in the color spectrum, and we know them well (save for those of us who are color blind). Above the violet and "out of sight" as it were are the ultraviolet (UV) frequencies. Then we'll see the X-rays and beyond them the gamma rays, which are the highest frequencies and the highest energy forms of EM radiation. Across all of the spectrum, the electromagnetic spectrum, we'll grab a band of frequencies and generate the waves to use them for different things. You already know the benefits of radio waves and microwaves. And you've used the optical spectrum all your life. X-rays are something you know of as well. And the gamma rays, which are generated by changes in atomic nuclei, pass through you all the time because of natural radiation. There is more to learn, and links are provided below to get you further down the road.

Answer 4

An electromagnetic wave is a wave radiated by an accelerated charge and which propagate through space as coupled electric and magnetic fields, oscillating perpendicular to each other and to the direction of propagation of the wave.

Answer 5

both, although this is hard to properly understand without getting confused.

Electromagnetic radiation is more or less nothing else than electromagnetic radiation which can be generated from a magnetic material. Every magnetic material is having this electromagnetic field. At least we can say that electromagnetic radiation is at a particle.

Perhaps the best simple answer to the question is: Yes.

And while you're wrapping your brain around that one,

we should point out that matter is too .

Answer 6

energy that can travel through space in the form of waves