Coulomb's law in vector form
Electric charges and fields · Physics
Electric field lab
Interactive 3DPlace charges and trace the field lines — like charges repel, opposites attract.
Controls
Drag the sliders or type a value — the simulation updates live.
µC
1µC10µC
Study notes
Two 5 µC charges, opposite signs, 10 cm apart: F = k·q₁q₂/r² = (9×10⁹)(5×10⁻⁶)²/(0.1)² ≈ 22.5 N attractive. Flip one sign and the same 22.5 N becomes repulsive — the field lines redraw themselves instantly. The field midway between opposite charges is E ≈ 2kq/r², pointing from + to −.