Electric field direction with an electron?

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SUMMARY

The discussion clarifies the behavior of electric fields and forces acting on charged particles, specifically electrons and protons, in an electric field created by two plates. The electric field lines point from the positive plate to the negative plate, indicating the direction of the field. For a proton, the force vector aligns with the field direction (downward), while for an electron, the force vector opposes the field direction (upward). This relationship is governed by the equation F = q*E, where F is the electric force, q is the charge, and E is the electric field.

PREREQUISITES
  • Understanding of electric fields and forces
  • Familiarity with the equation F = q*E
  • Knowledge of charge polarity (positive and negative)
  • Basic concepts of potential energy in electric fields
NEXT STEPS
  • Study the concept of electric field lines and their significance
  • Explore the implications of charge polarity on particle movement in electric fields
  • Learn about potential energy changes in electric fields
  • Investigate applications of electric fields in real-world scenarios, such as capacitors
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Students of physics, educators explaining electric fields, and anyone interested in understanding the dynamics of charged particles in electric fields.

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Homework Statement


If we have an electric field with a positive and negative plate:

The field lines will be going from the positive to the negative, so down.

But, if we put an electron between these two plates, it will be attracted to the positive plates, so it will have a force vector pointing up.

The electron has more potential energy at B and less at A

If the electron moves from point A to point B; was this caused by the field? Will the electric field move the electron from point A to point B, even though the electron wants to attract to the positive terminal?

So my basic question is: Will an electric fields force vector be DOWN for a proton and UP for an electron? Or will it always be DOWN (from positive to negative) no matter what? Thereby increasing the electrons potential energy?

+++++++++++++++++++++++
A

B
------------------------------



Homework Equations





The Attempt at a Solution


Not really sure at the attempt, because it's not really a question from my book, but more of a question from myself.
 
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Field lines are defined to point from positive to negative. If we draw out the lines, they'll point downward in your picture, as you said.

Now, let's remember how to relate electric forces to electric fields. If we have an electric field, E, and a charge, q, then the electric force, F, can be found with F = q*E. So if we put down a positive q (like a proton), the force will be in the direction of the field (since q won't change the sign of E). However, if we put in a negative charge (like an electron), the negative q value will cause the force to have an opposite sign from the field. We know that it will point in the opposite direction as the field.

We can see that this works. If the field lines point down, and we put in a proton, it will move down, which we just predicted. If we put in an electron, it will move up, as we just predicted and as you stated. This is actually why we use the convention of pointing field lines from positive to negative.

That's the relationship between fields and forces to remember. Does that make sense?
 
UVW said:
Field lines are defined to point from positive to negative. If we draw out the lines, they'll point downward in your picture, as you said.

Now, let's remember how to relate electric forces to electric fields. If we have an electric field, E, and a charge, q, then the electric force, F, can be found with F = q*E. So if we put down a positive q (like a proton), the force will be in the direction of the field (since q won't change the sign of E). However, if we put in a negative charge (like an electron), the negative q value will cause the force to have an opposite sign from the field. We know that it will point in the opposite direction as the field.

We can see that this works. If the field lines point down, and we put in a proton, it will move down, which we just predicted. If we put in an electron, it will move up, as we just predicted and as you stated. This is actually why we use the convention of pointing field lines from positive to negative.

That's the relationship between fields and forces to remember. Does that make sense?

Yes, thanks. I seemed to have gotten confused, but its clear now.
 

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