Electric Potential: Solve for Energy to Move -5uC Charge to Infinity

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SUMMARY

The discussion focuses on calculating the energy required to move a -5 μC charge from the origin to infinity in the presence of two other point charges: +8 μC at (-6,0) cm and -11 μC at (-5,-12) cm. The relevant equations used are V = KQ/R for electric potential and U = -qV for potential energy. The confusion arises from understanding why the energy potential is calculated without considering the -5 μC charge at the origin. The solution indicates that the work done is based on the potential created by the other charges, not the charge being moved.

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  • Understanding of electric potential (V) and potential energy (U)
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  • Basic proficiency in physics equations related to electrostatics
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  • Review the principles of electric potential and potential energy in electrostatics
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bob19841984
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Homework Statement



A point charge of +8C is located at (-6,0)cm. A second point charge of -11C is located
at(-5,-12)cm. If a -5C charge were at the origin, how much energy is required to move it to in nity?

Homework Equations



V=KQ/R
U = -qV


The Attempt at a Solution


I have the solution. It is given as below... I just don't understand why!
http://a-s.clayton.edu/jdyer/physics/phys1112/phys1112S09/Quizzes/1112_Quiz2_solution.pdf"

If the origin now has a -5 micro C charge, why is the energy potential still calculated as if it was not there? I have been banging my head on this for a while, any help would be greatly appreciated.
 
Last edited by a moderator:
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bob19841984 said:
1. T


The Attempt at a Solution


I have the solution. It is given as below... I just don't understand why!
http://a-s.clayton.edu/jdyer/physics/phys1112/phys1112S09/Quizzes/1112_Quiz2_solution.pdf"

If the origin now has a -5 micro C charge, why is the energy potential still calculated as if it was not there? I have been banging my head on this for a while, any help would be greatly appreciated.

V1 and V2 are the potentials at origin due to two charges. -5 μC charge is taken from origin to infinity and the work done to do this is -q*ΔV.
 
Last edited by a moderator:

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