Electrostatic Potential Energy Simulation
Two-charge system with and without external field
Example 2.5
(a) Calculate electrostatic potential energy of two charges (7μC and -2μC) 18cm apart. (b) Work needed to separate them infinitely. (c) Energy when placed in external field E = A(1/r²).
Isolated System
Potential energy:
U = (1/4πε₀)(q₁q₂/r)
U = -0.70 J
Work to Separate
Work required:
W = U_inf - U = 0 - U
W = 0.70 J
With External Field
Total energy:
U_total = q₁V(r₁) + q₂V(r₂) + U
U_total = 49.30 J
Key Concepts
- Potential energy of two charges: U = kq₁q₂/r
- Work needed to separate charges equals -U
- External fields contribute additional potential energy
- Energy is scalar - sum all contributions
- 1 μC = 10⁻⁶ C, 1 cm = 10⁻² m
