Electric field due to a charged particle at a random point in space

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Discussion Overview

The discussion revolves around the calculation of the electric field at a point in space, specifically addressing whether it can be determined even in the absence of charged particles at that point. The conversation touches on the relevant equations from electromagnetism and the roles of test charges.

Discussion Character

  • Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions if the electric field can be calculated at a point in space without the presence of charged particles, referencing a standard equation for electric fields.
  • Another participant clarifies that the equation provided is for the electric force on a test charge, not the electric field itself.
  • It is noted that the electric field produced by a source charge can be defined at any location, regardless of whether a test charge is present there.
  • A participant acknowledges a misunderstanding regarding the inclusion of the test charge in the equation.
  • Another participant expresses realization of the oversight in their earlier post regarding the equation's components.

Areas of Agreement / Disagreement

Participants appear to have differing understandings of the equations related to electric fields and forces, but there is no clear consensus on the initial question regarding the calculation of the electric field at a point without a charged particle.

Contextual Notes

There is a potential ambiguity in the definitions and roles of the test charge in the context of electric fields and forces, which may affect the clarity of the discussion.

Lukasz
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Can we calculate the electric field at any given point in space even if there are no charged particles there? The equation for electric field given in a standard EM course is kqq0/q0r^2 where q0 is a test charged impacted by the electric field. How about just any point in space?
 
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Lukasz said:
The equation for electric field given in a standard EM course is kqq0/q0r^2 where q0 is a test charged impacted by the electric field.

No, that's the equation for the electric force acting on q0.

The electric field produced by the source charge q, at the location of q0, is E = kq/r2, regardless of whether q0 is actually at that location or not.

When you put q0 at that location, it experiences a force F = q0E.
 
I think I posted an equation for an electric field as I included q0 in both nominator and denominator, and thanks for explaining, I thought so.
 
Oops, I saw the q0 in the numerator but missed the one in the denominator. :blushing:
 

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