Finding the Trajectory of a Test Charge in an Electric Field

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Discussion Overview

The discussion revolves around finding the trajectory of a test charge placed in an electric field, specifically considering the complexities introduced by non-uniform fields. Participants explore various methods and concepts related to this problem, including comparisons to gravitational fields and the implications of the inverse square law.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant suggests using the method for finding trajectories in gravitational fields but notes that the assumption of a uniform field may not hold in this scenario.
  • Another participant argues that the concept of trajectory for a test charge does not apply in the same way, suggesting that the two-body problem under the inverse square law is more appropriate.
  • A third participant clarifies that the force on a point charge in an electric field is directed along the line connecting the two charges, indicating that acceleration is also along that line.
  • One participant expresses difficulty in dealing with non-uniform fields, highlighting the recursive nature of acceleration and position, leading to the realization that a differential equation is necessary to describe the motion.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of trajectory concepts for test charges in electric fields, with some advocating for the two-body problem approach while others focus on the implications of non-uniform fields. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants note the complexity introduced by non-uniform fields and the recursive relationship between acceleration and position, which may require advanced mathematical treatment such as differential equations. There is also a lack of consensus on the appropriate framework for analyzing the motion of test charges.

tickle_monste
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Let's say I were to place a test charge, q0, in a standard electric field E = k*q1/(r^2).
How would I find the trajectory of the charge? I have been trying the method used for finding the trajectory in a gravitational field, but I believe the problem is that that formula (Gm1m2/(r^2)) assumes a uniform field, whereas in this smaller scale problem, no such approximation can be made. I'm not sure whether I should be looking for a differential equation or something like Newton's method or what.
 
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Hello

Test charges would keep still on the points during observation of electric fields by measuring the applied force/charge. In this sense trajectory of test charge does not make good sense to me. If you are interested in motion of charges, two body problem under square inverse law with parameters e1,e2,m1,m2, should be your case. I believe scale problem does not matter in square inverse law.

Regards.
 
I think you're talking about a point charge placed into a field generated by another point charge. The direction of the resulting force is along the line connecting the two point charges, therefore the resulting acceleration is along that line.

Gm1m2/r^2 is not for a uniform gravitational field. It's for the force between two point masses, which is a radial set of directions for field lines.
 
Well the problem I get when I don't assume a uniform field is that the amount of acceleration is a function of position. But the position is a function of acceleration which is a function of position etc.

*EDIT* so yea, I realize now that I'm looking at a differential equation
 
Last edited:

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