Читать книгу The ESD Control Program Handbook - Jeremy M. Smallwood - Страница 54

Like charges repel, and in a conductor where charges are free to move rapidly, charge will rapidly move to the outer surface to minimize their proximity to each other. After charge has redistributed, the voltage on all parts of the conductor is equal (equipotential). This must be so – current flows due to voltage differences, until the equipotential state is achieved.

For an insulating object, charge does not flow freely and so the voltage at each point on the surface is typically different from its neighbor. For intermediate materials, the time taken to achieve near equipotential surface is several times the time constant.

For objects that have high resistivity and a long time constant, charge will redistribute to equipotential if we wait long enough (and if the field source is not changing rapidly) – but in the meantime surface voltages can be different.