SECTION : Electrostatics      

An animation of the motion of a negatively charged particle attracted by the positively charged sphere of a van de Graaff generator. When the charge is moving away from the sphere and slowing down, its kinetic energy is decreasing and the energy is being stored in the local electric field as that field is stretched. When the charge is moving toward from the sphere and speeding up, its kinetic energy is increasing as the energy previously stored in the stretched field is released.