Physics · Electrostatic Potential

The electrostatic potential energy difference between two points \( R \) and \( P \) in an electric field is given by \( \Delta U = U_P - U_R = W_{RP} \). What is the physical significance of this quantity?

1. It depends on the absolute reference point chosen for potential energy.
2. Only the difference in potential energy between two points is physically significant, not the absolute value.
3. It represents the total mechanical energy of the charge-field system at point \( P \).
4. It is equal to the work done by the electrostatic field itself during the displacement.