Infinite Number of Image Charges?

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Discussion Overview

The discussion revolves around the concept of image charges in the context of grounded conducting planes and mirrors. Participants explore the implications of the alignment of these planes on the number of image charges generated, particularly focusing on scenarios where the planes are parallel versus slightly angled.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that with perfectly parallel planes, there are exactly two image charges, but questions whether misalignment leads to an infinite series of image charges.
  • Another participant argues that there appears to be an infinite number of images regardless of whether the mirrors are parallel, noting that the first image can obscure others.
  • A third participant confirms that the method of images applies, indicating that images of images can occur ad infinitum in both mirror and grounded plane scenarios.
  • One participant concludes that for perfectly parallel grounded planes, the number of image charges is infinite, while for angled planes, the number is finite and dependent on the angle, suggesting a net force on the charge towards the intersection of the planes.

Areas of Agreement / Disagreement

Participants express differing views on the number of image charges generated by parallel versus angled planes, with some asserting an infinite number of images and others suggesting a finite count depending on the angle. The discussion remains unresolved regarding the exact nature of the image charges in these configurations.

Contextual Notes

The discussion includes assumptions about the behavior of image charges and the conditions under which they are generated, but these assumptions are not fully explored or agreed upon by all participants.

bob012345
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Consider two opposing mirrors. If they are exactly parallel planes I think there is only a single image in each but if they are slightly angled there appears an "infinite" number of reflections. Similarly, suppose we have grounded conducting planes instead of mirrors with a charge in between them. I think if they are perfectly parallel there are exactly two image charges. But if they are slightly misaligned will there be an multiple series of image charges appearing to go to infinity? If so, will the actual number of images depend on the angle? Thanks.

p.s. Now I'm not sure if there are or aren't an infinite number of images when mirrors are exactly parallel. I can't see them since my own image blocks them.

p.s.2 On further reflection...Of course there must be.
 
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There are a seemingly infinite number of images whether or not the mirrors are parallel.
If you are looking straight into one of those mirrors, your first image will completely hide the others.
But stick your hand out to the side (with your arm bent - as if you were waving to yourself) and try counting how many images of your hand there are.
 
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bob012345 said:
Like a seeming infinite number of images occur in opposing mirrors, does a similar situation occur with opposing infinite grounded, conducting planes with a charge in between them?

Yes. It's called the method of images. (A far less known but similar method of images exists in magnetostatics.)

In both of your cases one gets images of images ad infinitum.
 
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Thanks. So for two perfectly parallel grounded, conducting planes with a charge in between, the number of image charges is infinite and any forces on the real charge cancel out. If the planes are angled the number of images is finite and should be dependent on the angle and there would be a net force on the charge acting towards the intersection of the two planes just as there is a force when a single charge is located near a single plane.
 

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