Physics · Electrostatic Potential

Based on the arrangement shown in Figure 2.1, when a test charge \( q \) is moved from \( R \) to \( P \) against a repulsive force, what does the integration \( W_{RP} = -\int_R^P \mathbf{F}_{\text{ext}} \cdot d\mathbf{r} \) physically represent?

1. Total work done by the electrostatic field
2. Total mechanical energy dissipated
3. Kinetic energy gained by the test charge
4. Potential energy difference \( U_P - U_R \)