Superposition of Forces

Pick a regular shape and drop charges onto its corners, the middles of its edges, or its centre. Give each charge a sign and a size. The arrow on every charge is the net force — the vector sum of the pushes and pulls from all the other charges. Put equal charges on every corner and watch the force at the centre vanish: that is symmetry at work.

Click a site to place a charge Click a charge to select it · double-click to remove Red +, blue −, brown arrow = net force

Figure

Sides 4 · square

New charge

Value +2 µC

This value is used for the next charge you place. Click an empty site to drop it.

Selected charge

Value – µC

Net force

— N

Direction

—

Click a charge to select and edit it.

On the board

Charges

Shape

square

Changing the number of sides clears the board, since the sites move.