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I understand that potential is for a point/space and potential energy is dependent on field which applies only when we have more than 1 charge.

But please consider this system of charges. Three point charges shown here lie at the vertices of an equilateral triangle. The question in the book is to find the electrostatic potential energy of this system of three charges - whether it would be positive or negative?

Now, what is the real significance of this potential energy of the 'system'? As I imagine, if I bring in a +ve charge from infinity to near the +ve charge in this system, it is going to get repelled. and vice-versa if I bring in a +ve charge from infinity to near the -ve charge in this system.

So, even if I calculate a value of potential energy for this 'system' (ex: -2 Joules), what does this value really signify?

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The potential energy means the amount of work done in bringing a charge from infinity to a point in present system of charges or simply the amount of work done to remove the charges apart

From your example let's say the potential energy of the system is -2J this means that we have to do a total work of 2J to remove any charge from system to infinity

if we have a system of 2 +ve charges say 'q' then their potential energy would be +ve means we have to do work in order to make the system stay in it's place because as the 2 charges are +ve they would repel each other and the charges will move apart

Hope it's clear you can comment if you have any confusion :)

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    $\begingroup$ The energy to remove any charge or to remove all charges? $\endgroup$
    – BowlOfRed
    Commented Mar 16, 2023 at 8:14
  • $\begingroup$ "The potential energy means the amount of work done in bringing a charge from infinity to 'a point' in present system of charges.." - This is exactly where my doubt is. In this system of charges, not all points are equal. If I bring a +ve charge from infinity to a point close to the +ve charge in this system, a work will have to be done to overcome repulsion. But If I bring a +ve charge from infinity to a point close to the -ve charge in this system, it would be vice-versa (attraction). So, when i calculate the system's PE as -2J, which point does it refer to? $\endgroup$
    – Janaaaa
    Commented Mar 16, 2023 at 8:23

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