Why Do Electrons Move Toward Higher Electric Potential?

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SUMMARY

The discussion centers on the behavior of electrons in an electric field generated by a positively charged infinite plane. The electric field (E) is defined as E = (σ)/(2ε), indicating a uniform field where the force on a test charge remains constant. When a positive charge moves towards the plane, it decreases its potential energy and electric potential. Conversely, an electron, which possesses a negative charge, moves towards the plane, resulting in a decrease in its potential energy (more negative) while simultaneously moving towards a higher electric potential, which is counterintuitive. The key takeaway is that for electrons, lower potential energy corresponds to a more negative value, thus clarifying their movement towards higher electric potential.

PREREQUISITES
  • Understanding of electric fields and potential, specifically the concept of electric potential energy.
  • Familiarity with charge types (positive and negative) and their interactions in an electric field.
  • Knowledge of the relationship between electric field strength and charge density (σ) in electrostatics.
  • Basic principles of electrostatics, including the behavior of test charges in electric fields.
NEXT STEPS
  • Study the concept of electric potential energy and its mathematical formulation in electrostatics.
  • Learn about the implications of charge polarity on movement within electric fields.
  • Explore the relationship between electric field strength and charge density in greater detail.
  • Investigate the concept of equipotential surfaces and their significance in electric fields.
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone interested in understanding the principles of electrostatics, particularly the behavior of electrons in electric fields.

NJDevilsFan26
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Hey,

So I pretty much don't understand why certain concepts work when dealing with electric potential.

Suppose we have an infinite plane with some positive charge density, and the magnitude of the E field at an distance z from the plane is defined as E = (σ)/(2ε) (so the field is uniform and the force exerted on any test charge is always the same, regardless of distance).

If we place a positive charge near the surface of the plane, it will have high potential energy and move in the direction towards lower potential energy and lower electric potential.

Now, if we place an electron at some arbitrary distance above the plane, it will move towards the plane. So in theory, it will be moving towards lower potential energy (this I understand) and higher electric potential (this I do not understand at all).

How can it be moving towards higher electric potential when the potential energy is decreasing the closer it gets to the plane? I understand how it works with a positive charge, but not with a negative test charge.

And I know that in general, the rule is that electrons move toward lower potential energy and higher electric potential, but I want to understand why. The idea with the electron seems so counterintuitive to me.

Any help is appreciated. Thanks.
 
Physics news on Phys.org
Although the potential is positive from a positive source, the potential energy is negative for an electron in a field from a positive source. In this case "lower" potential energy means a more negative value.
 

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