SECTION : Van de Graaff  

An animation of the motion of a positively charged particle repelled by the positively charged sphere of a van de Graaff generator. When the charge is moving toward 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 compressed. When the charge is moving away from the sphere and speeding up, its kinetic energy is increasing as the energy previously stored in the compressed field is released.