How Do Electric and Magnetic Forces Interact with Charges?

AI Thread Summary
Electric and magnetic forces interact with charges in a way that depends on the frame of reference. When two charges are accelerated in a box, an observer inside measures one electric force, while an external observer measures a greater force due to the effects of acceleration. The net force observed must account for a magnetic force acting in the opposite direction, which balances the measurements. The discussion emphasizes that the movement of the charges is relative to each other and the box's walls, influenced by their mutual attraction or repulsion. Understanding these interactions is crucial for grasping the principles of electromagnetism.
kent davidge
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(sorry my bad english)
Let's imagine two frames of reference, one of which is a imaginary room containing two charges. Now let's accelerate this room from 0 to v and keep that speed during some time interval t and then we "pause" the situation again. An observer inside the box would measure the electric force acting on the charges and the observer in the other frame would measure a greater electric force. But the final positions of the two charges after time t should be the same as seen by all observers. So, there must be a force acting on the opposite direction as seen by the observer outside the room, that decreases the net force, and that force is what we call magnetic force.

Is it correct to think so?
 
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Assuming you mean the 2 charges are just floating in the box ...
(ie not in physical contact with the inner walls of the box)

now it doesn't have to be charges ... it could be 2 of anything
what do you think will happen to those 2 objects when you accelerate the box ?

Dave
 
davenn said:
Assuming you mean the 2 charges are just floating in the box ...
yes
davenn said:
what do you think will happen to those 2 objects when you accelerate the box ?
Okay. I just wanted to think of a box as being in one frame of reference, but let's forget it. Just think that the 2 charges start moving.
 
kent davidge said:
Just think that the 2 charges start moving.

I think you missed what I was trying to hint to you
They will only start moving relative to each other and the walls of the box if there is a mutual attraction or repulsion between them
That's even if the box isn't moving.
 
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davenn said:
I think you missed what I was trying to hint to you
:biggrin:
 
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