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A proton moves away from an electron. What would be the change in the potential energy of this system?

Asked in GUJCET 2016 · Energy of a system of charges

Answer: (2) increases

Step-by-step solution

For two point charges, U=(kq₁q₂)/r.

Proton and electron: q₁q₂=(+e)(-e)=-e², so U=-(ke²)/r, a negative quantity.

As they separate, r increases and U becomes less negative — it increases towards zero.

Physically, they attract, so pulling them apart needs work done on the system, and that work is stored as potential energy.

So the potential energy increases.

Why the other options are wrong

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