question about the wave model of EM fields

[gib65]

Hi all,

 

First off, I'd like to thank all moderators and members of this forum for answering my questions in the past, as they've shed tons of light on my understanding of the world.

 

Anyway, here comes another one. I've been reading through the particleadventure website (highly recommended) and I stumbled across a certain model for how electromagnetic fields interact with particles to give them a push:

 

http://particleadventure.org/particleadventure/frameless/accel_ani.html

 

According to this model, particles "surf" the electromagnetic wave. But after thinking about this, I can't conclude anything other than that this model only works when the charge of the field and the particles are the same. That is, positive fields will repel positively charged particles and negative fields will repel negatively charged particles. But what happens when the charges are opposite? The particles would obviously have to move towards the source of the field. But then what of the surfing-the-wave analogy? Do the waves travel inwards, converging upon the source of the field? Would they be coming out of pure space?

 

But that's not exactly the crux of the problem. The problem is when you start talking about particles attracting other particles (get rid of the field). For the sake of my question, I'm going to assume outward eminating waves correspond to a negative charge and inward converging waves correspond to a positive charge (the reverse case would yeild the same problems, so it doesn't matter). So then, electrons with their negative charge would repel each other via mutual wave-surfing of each others outward propagating fields. No problem there. But now protons should attract each other!!! Protons being positively charged should have inward converging waves and thus, if they are to surf each other's waves, pull each other closer. Furthermore, you take any two particles with opposite charges and you should see a chase. Take and electron and proton (again). As the proton attempts to pull the electron in with its inward converging waves, the electron pushes away with its outward propagating waves. The result is that you should see the electron chasing the proton.

 

Of course this is all incorrect. So my question is, what's wrong with my understanding of this model? Is there something wrong, or is it just that the model is limited to repelling EM fields?

 

Gib

[[Tycho?]]

I've never heard anything like this inward and outward wave stuff, it obviously doesn't work too well, since like charges always repel, and opposite charges attract.

 

A particle at rest does not emit waves period. EM radiation is caused by occsilating magnetic fields, or and change in velocity of an electromagnetic field (like an electron). So if you have an electron moving back and forth, it will be emmitting EM radiation on a certain frequency. If it is still, or moving at a constant velocity, it emmits no waves. Waves are not required for particles to attract or repel eachother.

 

I hope this helps, since I'm not really sure what the problem here is.

[gib65]

It does help, sort of. I was just going by what the website said (see link in my previous post). If you read just that one page, it seems to be saying that in a particle accelerator, magnetic fields are used to get particles moving. Now I assume that in order for this magnetic field to move particles, the magnetism involved is the same thing as the electromagnetic field surrounding charged particles, and thus has positive and negative values, and that if it is used to push particles away it is essentially the same thing as a charge whose value is the same as the particles being pushed.

 

It just gets confusing when they start talking about the particles "surfing the wave" because then the dynamics seem much more mechanical, and you get all the conundrums described in my previous post.

[gib65]

Sorry, I just checked that link again, and it would be more informative to also read the one before it:

 

http://particleadventure.org/particleadventure/frameless/accel_particles.html

 

This is where they actually mention particle that "ride" the wave like surfers.