2 Q's: EM radiation produced by positive charge

AI Thread Summary
The discussion revolves around two questions regarding electromagnetic (EM) radiation produced by an oscillating electric charge. The first question addresses the significance of the electric and magnetic components in EM field graphs, emphasizing that these graphs illustrate both the magnitude and direction of the fields. The second question pertains to the appearance of the graph when the charge oscillates, with sinusoidal oscillation yielding sinusoidal graphs. Participants clarify that the electric field direction aligns with the charge's motion, while the magnetic field behaves differently, complicating the understanding of their relationship. Overall, the conversation highlights the complexities of visualizing and interpreting EM radiation graphs related to oscillating charges.
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I have 2 questions about EM radiation produced by an occilating electric charge.
Q1: With graphs of electromagnetic fields, you can see that it contains an electric and magnetic component. What does these mean or give information about?
Q2: By occilating the charge, you will get such a graph. How will it look like?

I have tried drawing, doing research on the Poyting vector and I keep finding that the magnetic field will be in the opposite direction on the graph, in the case of the positive charge. And I sure know how to find the direction of a magnetic field...
 

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Q1. these graphs give information about the electric and magnetic fields... what don't you understand?
Q2. How the graph looks depends on how you oscillate the charge ... if you oscilate the charge sinusoidally, for example, you will get sinusoidal graphs.
See: http://www.cco.caltech.edu/~phys1/java/phys1/MovingCharge/MovingCharge.html

You are given a position-time graph for the charge; what does the acceleration-time graph look like?
 
Simon Bridge said:
Q1. these graphs give information about the electric and magnetic fields... what don't you understand?
Q2. How the graph looks depends on how you oscillate the charge ... if you oscilate the charge sinusoidally, for example, you will get sinusoidal graphs.
See: http://www.cco.caltech.edu/~phys1/java/phys1/MovingCharge/MovingCharge.html

You are given a position-time graph for the charge; what does the acceleration-time graph look like?

With the picture I attached, you can find the EM graph aswell. What I don't understand about that graph is wether it's the direction or magnitude of the the field. I have tried understanding what the graph of a charge moving sinusoidally look like, but it's inconsistent with for example the Poyting vector.
 
The example EM graph on what you supplied shows both the magnitude (the line) and the direction (the arrow). That is why the E and the B curves are drawn perpendicular to each other.

The graph of the sinusoidally moving charge is given to you in thr same picture - top right - as y vs t. This is a position-time graph. There is nothing wrong with it.
 
Simon Bridge said:
The example EM graph on what you supplied shows both the magnitude (the line) and the direction (the arrow). That is why the E and the B curves are drawn perpendicular to each other.

The graph of the sinusoidally moving charge is given to you in thr same picture - top right - as y vs t. This is a position-time graph. There is nothing wrong with it.

So when the charge moves up, the electric field moves up?
The magnetic field move in a circle when it moves up, but it's in the other direction when moving up, that's the problem I run into.
 
The electric field moves along, not up and down.
The magnitude may increase and decrease with time, and it may change direction.

How is the electric field related to the motion of the charge?
Don't guess - if you don;t know, look it up. I gave you a link even.
 
Simon Bridge said:
The electric field moves along, not up and down.
The magnitude may increase and decrease with time, and it may change direction.

How is the electric field related to the motion of the charge?
Don't guess - if you don;t know, look it up. I gave you a link even.

Took me some time to get the applet running, but now I can grasp it. Thanks!
 
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