Electric Potential: V=-ED for Capacitors?

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SUMMARY

The change in electric potential between two capacitor plates is accurately represented by the equation V = -ED, where E is the electric field and D is the displacement. This relationship holds true as the electric field points from the positive to the negative plate, indicating a decrease in potential when moving in the direction of the field. The dot product of the vectors ensures that the sign of the potential change is correctly accounted for, confirming that moving along the electric field results in a negative change in potential.

PREREQUISITES
  • Understanding of electric fields and their directionality
  • Familiarity with the concept of electric potential
  • Knowledge of vector dot products
  • Basic principles of capacitors and their operation
NEXT STEPS
  • Study the relationship between electric fields and potential in different geometries
  • Explore the concept of capacitance and its dependence on plate separation
  • Learn about the applications of capacitors in electrical circuits
  • Investigate the effects of dielectric materials on electric fields and potential
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Students studying electromagnetism, electrical engineers, and anyone interested in understanding the principles of capacitors and electric potential differences.

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Homework Statement


Why is the change in the electric potential between two capacitors V=ED ?


Homework Equations



V=-ED

The Attempt at a Solution



Isn't the change in electric potential equal to the negative of the product of the electric field and displacement?
So, why is it that for a capacitor the change in potential is not V=-ED ?

Thanks for any help.
 
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You mean the change in potential between the 2 plates of a capacitor?

Actually the equation \Delta V = -E \cdot D is satisfied

E \cdot D is the dot product of the vectors of the electric field and the displacement.
It's +|E||D| if they are in the same direction and -|E||D| if they are in opposite directions.

(|E| is the magniture of the electric field |D| is the magnitude of the displacement)

In a capacitor, the electric field points from the positive plate to the negative, so from the higher potential to the lower. If you move in the direction of the electric field, then both E and D have
the same direction, but you're moving to a lower potential, which is as it should because -E \cdot D is negative
 

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