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This application simulates the dynamics of free charges in a conductor. It is possible to observe the tendency of charges to accumulate on the surface of the conductor, leading to a charge density zero inside the conductor.

Use the usual touchscreen gestures:

• With one finger, hold and drag to move the loads around.

Buttons:

• Starts or pauses the simulation.
• Restarts the simulation.

The movement of charges is based on Newton's second law and Coulomb's law of electrostatics. The resultant force on charge $q_i$ is given by

$\vec{F}_i = \dfrac{1}{4\pi\epsilon_0}\sum_{j \neq i}^N \dfrac{q_iq_j}{r_{ij}^2}\hat{r}_{ij },$

where

• $N$: number of free charges
• $\epsilon_0$: electrostatic vacuum constant

The movement of the charges is damped by a force proportional to the speed: $\vec{F}_\gamma = -\gamma \vec{v}$

The ODE system is solved by the fourth order Runge-Kutta method.

Other considerations:

• The values ​​of $q$, $\gamma$ and the mass of the charges are given in arbitrary units.
• Collisions of charges with the boundary of the conductor are partially elastic.

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