Coulomb's law – force between two charges

PhysicsElectric & Magnetic FieldsAges 16–17

Two charges sit on an axis: drag them directly or use the sliders to change the magnitude (including the sign) of q₁ and q₂ and the distance r between them. The Coulomb force is shown by arrows and as a number, changing colour and direction depending on whether the charges have like signs (repel) or opposite signs (attract). The Macro screen uses microcoulombs and metres, like everyday static charges; the Atomic screen scales down to the elementary charge e and picometres, as in atoms and molecules. The force can be shown in scientific notation a×10ⁿ or as a decimal, and "Constant charge size" separates the drawn size from the real charge magnitude. Based on the "Coulomb's Law" simulation by PhET Interactive Simulations, University of Colorado Boulder (CC BY 4.0); rewritten.

Lesson: Forces between electric charges