Do we know how electromagnetic fields work.. do we REALLY know?

Question

I can not find an answer for this. I look up the definition an electromagnetic field and it just describes it as being caused by "The electric field is produced by stationary charges, and the magnetic field by moving charges (currents); these two are often described as the sources of the field."

Now tell me this, is this cause theoretical or proven? Also, moving charges?? I always found physics to be very vague (I'm a genetics major). What do they mean by waves? Yes I took physics I know what a wave is. But HONESTLY what is a wave at the most subatomic level. For example in molecluar biology we can tell you how transcription occurs at the protein level.

I mean, what is radio waves?? How does a wave become music to our ears. I do know that our ears take in the waves and our brain processes each distinct series of waves as a 'sound' but how does do these series of waves travel so distinctly??

man I hope this doesn't come off as a bunch of rambling.. lol

david, thanks for giving a good answer.

The other two folks, thanks for the explanation as well. You both described the processes using definitions. David broke it down to admit that we don't know the truth at the most fundamental level. After all, it is a scientific theory.

Maybe one day we'll have the tools to really understand these things.

Answer 1

You're a genetics major and you call physics vague?

Beyond simple Newtonian mechanics, electromagnetism is the best understood area of physics, with few ambiguities and mysteries. The math is straightforward and well developed. Predictions are extremely accurate and reliable. If you're looking for a field of physics where we really don't know how it works, look at gravity.

Answer 2

Consider a radio wave from an FM broadcast transmitter operating at 99.9 MHz. The wave consists of electric and magnetic fields, each of which, by its change, creates the other, also changing. The wavelength of the waves is 3 meters, so you get an alternation of the field every 1.5 meters. The magnetic field is similar to that created by a permanent magnet or electromagnet; you can see the field lines by using iron filings. The electric field is similar to that generated by many sources, such as the raindrop motion that causes a thunderstorm to produce lightning. Maxwell's equations describe how the change in each field creates the other.

For a radio wave to carry information, it must be modulated: some property of the wave, such as its amplitude, frequency, or phase must be changed. FM means frequency modulation, so it is the frequency which is changing. The receiver knows what the basic frequency is (you told it with the tuning dial), and it produces sound based on the changes.

Light is also an electromagnetic radiation, of much higher frequency. Because the frequency is so high, quantum effects come into play: light has particle properties as well as wave properties.

Answer 3

I'll answer the radio wave turing into music bit for you first.

We don't hear (or even sense) radio waves. In fact, what happens is that sound is recorded electronically and then used to modulate (either frequency or amplitude) a radio wave. These radio waves are transmitted and picked up by a receiver which then demodulates back into an electrical frequency which in turn drives the speaker in your radio.

As to the first part of your question - do we REALLY know. The answer is no, we don't. What we have is a set of theories that describe the observed behaviour and allow us to model and predict this behaviour very accurately. That's what a theory does - it describes what we see. A scientific theory can never be proven to be true, only proven to be false (by the first valid example we come across which does not comply with the theory). At this point, the theory needs to be reviewed and adapted.

Waves vs. particles - well that get's really blurred at the atomic level because quantum mechanics works well in some cases describing things as particles and other times as waves. A good example of this is electrons which can be shown as particles - a stream of electrons hitting a solid can be shown to impart force as they rebound; or as waves - they can be diffracted. This is something that people sometimes have a great deal of problem understanding. I think it's one of those things that you either "get" or you don't - but if you keep at it, eventually it clicks into place and you have your Eureka! moment.

Answer 4

We know just about every characteristic of a magnetic field - from Faraday's early discoveries and formulas to modern day research - but we don't know what a magnetic field is.

Waves that you boogie to are merely the air compressions and expansions from the source.
The radio waves that bring you this music is merely the same information at a much higher frequency and are electromagnetic waves which are converted to audio frequencies, amplified and sent on to another magnetic transducer - the speaker.

Answer 5

We know the effect of electromagnetic fields and we know how they work through Maxwell's equations, Lorentz's Force Law and Faraday's laws of induction.

And we know how to create electromagnetic fields.

When engineers want to refine Plutonium into fissionable material they need to create heavy magnetic field centrifuges.

Quantum physics describes the propogation of electronic fields as a manipulation of photons.

Electromagnetic fields are convertible to electricity by inducing charged particles, or can be generated from charged particles.

But do we really understand it? Ahhhh. Yes and no. No more than gravity I'm afraid.

Answer 6

Hey Ibrahim.... you did ask of an EM (Electro-Magnetic) wave.
But, let me begin with the later part of the very ques.
1) Wave : Wave Motion, in physics, mechanism by which energy is conveyed from one place to another in mechanically propagated waves without the transference of matter.
Again, formally stating, a wave is something u see well in the ocean or sea, save the longitudinal waves. Here I mean that there are actually 2 sorts of waves : a) Transverse : These are of the sort u see on the sea, wave in which the direction of the displacement is at a right angle to the direction of the wave motion.A transverse wave may be mechanical, such as the wave projected in a taut string that is subjected to a transverse vibration ; or it may be electromagnetic, such as light, X ray, or radio waves.

b) Longitudinal: The longitudinal wave is always mechanical because it results from successive compressions (state of maximum density and pressure) and rarefactions (state of minimum density and pressure) of the medium. Sound waves typify this form of wave motion.

Some mechanical wave motions, such as waves on the surface of a liquid, are combinations of both longitudinal and transverse motions, resulting in the circular motion of liquid particles.
For a transverse wave, the wavelength is the distance between two successive crests or troughs. For longitudinal waves, it is the distance from compression to compression or rarefaction to rarefaction.

This was a breif discussion on waves.

2) Let me come to the main part of the question. You have inquired of the mechanism of the EM waves. Rather I appreciate that you enquired, as not many do.
Let me make you sure that EM waves are, as suggested by Max Planck, a mutual congregation of both, the Electric and the Magnetic feild. Regarding the phenomenon of their origin, lets visit the atom. You may be aware of the concept of exciting electrons. Its these electrons which absorb in the excess energy around and rise to higher shells of their orbit, around the nucleus. But, their quantum state prompts them to recede back to their original levels. Now you 'd ask me what happened to that energy, as it cant be simply ignored. Its this energy that is then emitted by the receding electrons as RADIATIONS or the EM waves. Now,
How 2 feilds come togather,.... simple. The electron has a certain charge(Generating the electric Feild) and motion too(leading to a Magnetic Feild). As you have stated, This is a well developed but yet THEORITICALLY accepted concept.

Let me make it sure that this is the reason we 've 3 cocepts regarding the EM waves, 2 Of which are accepted.
a) The wave concept : all what I explained formerly.
b) The Corpuscular Concept : Suggested by Sir Newton, It proposes that the EM wave is inbuilt of particles, but as we know these waves are massless, so the concept doomed.
c) The Quantum Approach : Its a retreat of the Newton's particle concept, But the candidate here is a PHOTON, or a quantum (packet) of energy. The same process of excitation of the electron works here. But rather the electron here ejects these photons and not waves.

But today, we see the dual effect, and we are bound to accept both, the wave as well as the photon theory, because some of the phenomenon related to these EM waves can be explained only by the wave theory(as interference, inference, polarization etc.), while the rest with the photon one(as photoelectric effect - proposed by Albert Einstein).

3) Let me end up with the last part....... sound waves are the longitudinal waves and require a medium to propagate, say air. They vibrate the molecules of air ... which in turn vibrate our eardrums. These vibrations are sensed by the motion of the hammer, which moves the anvil(both are the bone of the middle ear), which in turn moves the stirrup. As sound vibrations pass from the relatively large area of the eardrum through the chain of bones, which have a smaller area, their force is concentrated. This is the way they make the vibrations reach the inner ear and then to brain ( you know the story better.)

Bye ........ and PHYSICS IS THE MIRACLE OF THE LORDS (do remember)

Answer 7

Yea I don't think science knows about magnetic fields. It can say what makes them (magnets! who knew?!) and describe their effects, but WHAT IS the invisible hand that makes two atoms suddenly come together from a distance? Are they attracted to each other because they are in love? Because... magic? We might as well say any one of these. Fields are a total mystery. Perhaps as dark matter and energy become elucidated there might be some light thrown upon this hidden variable.

I've been asking around too and have hence come to this conclusion. But someone please correct me if I'm wrong here. I'm way out of my field. Ha! But I have certainly noticed a resistance among scientists and science-ists to simply admitting our collective ignorance on this issue at first, and then eventually having no other course but to agree. I think we should all remember that its what we don't know that keeps this whole learning thing moving. Some of the greatest minds in history were the humblest in regards to the limits of human knowledge. Einstein comes to mind.
Oh, by the way: https://www.youtube.com/watch?v=zn7-fVtT16k