Coulomb's Law
Release a second charge from rest near a fixed one — adjust both charges' sign and size and the starting separation to see it attract or repel exactly as F = kq1q2/r² predicts.
Preview — sign up free to change the numbers yourself
What you can adjust
- Fixed charge (q1)
- -10 – 10 µC
- Released charge (q2)
- -10 – 10 µC
- Initial separation
- 0.05 – 2 m
Pinned in place at the left. Positive (red) or negative (blue) — its sign, combined with q2's, decides attraction or repulsion.
Released from rest at the chosen separation and free to move along the line joining the two charges — same sign as q1 repels, opposite sign attracts.
Starting distance between the two charges — Coulomb's law falls off as 1/r², so closing this gap even a little sharply increases the force.
About this simulation
What it shows
One charge is fixed and a second is released from rest near it. Arrows show the force between them, and the second charge moves away or towards the first.
The key idea
Like charges repel and opposite charges attract, with a force F = k q₁ q₂ / r². The force falls off with the square of the distance, so halving the distance makes it four times stronger.
Try this
Halve Initial separation from 0.5 m to 0.25 m: the force on the released charge becomes four times larger.