What exactly is an electromagnetic wave physically?

Question

I understand how an electromagnetic wave works and what it does and all about the electromagnetic spectrum and all, but what exactly is it in its essence? What is it made of? What is physically happening on an atomic level? We've all heard the example of the waves in the oceon but how does it move throuh the vacuum of space? Thanks

Answer 1

http://www.colorado.edu/physics/2000/waves_particles/index.html

The wave, or "disturbance," is in an invisible thing called the electric force field. To understand electric forces, we have to learn something about charged particles like electrons and protons. Without these charged particles, there can be no electric force fields and thus no electromagnetic waves.

Answer 2

electromagnetic waves are regions of space where magnetic and electric fields are oscillating exactly 90 degrees out of phase. Under the right circumstances, these oscillations have the curious property of being able to propagate over distances, which is why we end up with electromagnetic radiation.

The most basic description, though, is a point in space where both fields are going back and force. There is no matter involved in classical physics, and under most real-life circumstances, light has primarily wave-like properties.

Of course, this begs the question of "what is a field?" The only good answer I can give is that it is a measure of how strong and in what direction some force is pushing or pulling.

A good though experiment is to imagine a very light, charged particle, like an electron, sitting in an empty room. If you start an electromagnetic wave where it is sitting (say, by shining a flashlight at it), you will actually see the electron being pushed back and forth by the electric field of the EM wave. Likewise, if there was such a thing as a super-light magnet, it would be pushed back and forth by the oscillating magnetic wave.

This is, in fact, how antennas work--the metal in them has electrons that are pushed back and force by passing radio waves, and we can measure how fast they are being pushed and pulled to figure out the signal.

In short, there is no physical manifestation of EM waves under most real-life circumstances. The are truly an example of "action at a distance," where objects can affect each other without touching each other (at least until you get into quantum mechanics, which is a whole other story).

Answer 3

A charged particle such as the positive nucleus of an atom in the sun emits an electric field in all directions. Now if that particle jiggles back and forth continually over time then the electric force at any particular point in space change from a slightly stronger force to a slightly weaker one and back again over that timespan (wave length). In other words the strength of the force oscillates back and forth and can be represented mathematically with a wave function. With a changing electric field there is a corresponding changing magnetic field because they are in some ways like two sides of the same coin.

Answer 4

Think of a simple wave : at the sea side when the tide is coming in. Next wave comes in further than the previous one but then a smaller one comes in but the tide is still generally coming in. Better still, think of dropping an object into a still pool of water. You can see the ripples starting from the point where the object hit the water expanding out to fill the pool. But then after a time the ripples get fewer and the pool starts to quieten down again and the ripples get less so drop another object in and the ripples start again. These ripples are waves. The more energy contained in the ripples, which can be varied by the size of the object, the height it fell from, its initial force (did you drop it or throw it), could determine how long they would continue to form and how far the ripples went. The same happens in other energy forms. I know you possibly wouldn't see energy moving in outer space as it is regarded as a vacuum, but you could feel it. Remember the ripple waves in the pool aren't really moving through the pool; it only demonstrates that the energy is there. That's the simplest way I can think of explaining it although I do appreciate there is more to it but way beyond Yahoo answers.

Answer 5

An electromagnetic wave is the wave version of the particle called a photon. Remember that at the atomic level everything has both a wave and a particle nature. In a sense the EM wave is a probability wave of photon density.

Answer 6

Vibrations of atoms perhaps because it is a wave of energy that is not actually made of any particular atom like e.g. light being made up of photons.

Answer 7

10 points on the crackpot index, rule 17

Answer 8

the best way :lectures of physics,Richrd Feynman.
or many such a book .
(we.in answer,repeat our feelings,and i saw very poor thy are)
i have studied magnetism,but i dont allow myself to speak of
the existence of physics, i am sorry,