Radial dependencies with electric field

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SUMMARY

The discussion focuses on the differences in electric field behavior from various charge distributions: a ring of charge, a line of charge, and an infinite plane of charge. It establishes that the electric field (E) from a ring of charge decreases with the inverse square of the distance (E ∝ 1/r²), while the field from a line of charge decreases linearly with distance (E ∝ 1/r). The reasoning provided indicates that as the distance increases, the ring behaves like a point charge due to the increasing surface area of nested spheres, while the line maintains a consistent field strength due to its geometry. This analysis clarifies the relationship between charge distribution and electric field strength.

PREREQUISITES
  • Understanding of electric fields and charge distributions
  • Familiarity with the concepts of inverse square law and linear relationships
  • Knowledge of basic electrostatics principles
  • Ability to visualize three-dimensional charge configurations
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  • Study the mathematical derivation of electric fields from point charges and continuous charge distributions
  • Explore the concept of Gauss's Law and its application to different charge geometries
  • Investigate the behavior of electric fields in three-dimensional space, particularly for cylindrical and planar geometries
  • Learn about the implications of electric field strength in practical applications, such as capacitor design and electric field mapping
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Students of physics, electrical engineers, and anyone interested in understanding the principles of electrostatics and electric field behavior in various charge configurations.

kiwibird4
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so for uniform charge densities, a point "r" from the center of a ring of charge has an
E ∝ 1/r^2
a point "r" from center of a long line of charge has an
E ∝ 1/r
and for an infinite plane, a point "r" from it where r<<length of plane has
E not dependent on r

my question was why is it that a ring of charge has an inverse square proportionality compared to a line of charge? Does the point have a stronger dependency on distance because there is "more area" of a ring then simply a line's electric field?

Also, when I think about r becoming extremely large (so the point is very far away), wouldn't the ring of charge be more like a point charge but why would the line be seen less as a point charge since it is not an inverse squared dependency but an inverse linear dependency (if that even makes any sense)
 
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For a ring of charge, when up close, the available charge would be producing an electric field in an ever growing series of nested cylinders. The area of the cylinders growing by the equation 2*r*pi.The drop off in field strength would thus be linear. As the ring receeds in the distance, it appears as a receeding point, thus the charge must be supporting a series of nested spheres, growing in surface area by 4*pi*r^2. The electric field thus dropping off by the inverse square rule. For the field near an infinite plane of charge, the charged plane supplies planes of the same size as the distance increases thus the field strength does not change.
 
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I have a common plasma globe with blue streamers and orange pads at both ends. The orange light is emitted by neon and the blue light is presumably emitted by argon and xenon. Why are the streamers blue while the pads at both ends are orange? A plasma globe's electric field is strong near the central electrode, decreasing with distance, so I would not expect the orange color at both ends.

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