Negative electrostatic potential energy

AI Thread Summary
The discussion revolves around the concept of negative electrostatic potential energy in a system of three point charges arranged in an equilateral triangle. The calculated potential energy of the configuration is -0.12 J, indicating that if the charges are released from rest, they will move closer together to further decrease their potential energy. This principle is explained by the idea that negative potential energy signifies stored energy, which can be released by allowing the charges to fall together. The analogy with gravitational potential energy is noted, highlighting the lack of terrestrial examples of negative potential. Ultimately, the movement of the charges toward each other serves to lower their potential energy, making it more negative.
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I have an example in my book showing 3 point charges each at the vertices of an equilateral triangle. q1 = +2 microC, q2 = -2 microC, and q3 = +1 microCoulombs. the distance between each is 0.30m. The example calculates the electrostatic potential energy of the charge configuration, obtaining -0.12 J. The example says that because the electrostatic potential is negative, if the charges were released from rest, they would fall together, not fly apart. "They would fall together, because this would lower their potential energy still further (a larger negative value)." I'm having trouble understanding this principle of negative potential energies. Can someone explain this to me? What does it mean exactly to have negative potential energy? I know there can be a negative change in potential energy, and that is easy to understand using the similar gravitational potential energy. And why must the charges fall together, and why must the potential energy be lowered by having a larger negative value?
 
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It might be easier to think of it in terms of the work done in order to bring those charges to the points that they are at from a point of rest. The problem with using gravitational potential as a source of experience is that there is really no terrestrial object that has a negative potential with respect to the earth, i.e. there is no terrestrial massive object that requires positive work to be done to move it from a point infinitely far away to near the earth.
 
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Okay, I think I have an understanding about the negative electric potential energy. But why would the charges fall together if they were released from rest?
 
Negative potential of any system just signifies that 'energy is stored in the system' , and if we want to extract the energy in this particular system of yours , we need to lower the energy stored in the configuration (by c.o.e) , this is done by making the Potential energy less negative , that is taking the charges as far apart as possible ...

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