Static Electricity Simulator (2D, Triboelectric Charging)

Rod material

Rubbing cloth

Rubbing

Rub duration 2.0 s

Pick a material pair and rub — series distance sets how much charge transfers.

Live readout

Rod charge Q

0.0 nC

Electroscope leaf angle

0.0°

Force on nearest bit

0.00 µN

Force on balloon

0.00 µN

How this simulation works

Rubbing two materials transfers electrons according to their position on the triboelectric series: the further apart the two materials sit, the more charge moves per rub, and the charge saturates over time rather than growing without limit — a real electret only holds so much surface charge before leakage matches transfer. The rod's accumulated charge Q (in nanocoulombs) is a genuine quantity, not a cosmetic number.

Every attraction you see obeys Coulomb's law, F = kq₁q₂/r². The paper bits and the balloon are electrically neutral, so their "charge" here is the induced charge a real field produces by polarising them: q₂ = αE, where E = kQ/r² is the rod's own field at that point. Substituting back gives F = kQq₂/r² — the same inverse-square law, evaluated with a physically induced second charge, always pulling the neutral object toward the field source. That is exactly why a charged balloon or comb picks up paper without ever touching it.

The electroscope's two foil leaves are wired to the rod and carry half of Q each. They spread until the Coulomb repulsion between them balances gravity's restoring torque: mg·tanθ = k(Q/2)²/(2L sinθ)², solved here numerically every frame rather than faked with a fixed lookup curve — which is why the deflection response is nonlinear, just like a real gold-leaf electroscope.

Drag the charged rod near the paper bits or the balloon