Final answer:
In the Van de Graaff and similar demonstrations, charges are transferred by contact and induction, where electrons are moved to a metal sphere or other objects, causing static electricity effects.
Step-by-step explanation:
In demonstrations such as the Van de Graaff generator, fur and rod, or shoes on a carpet, charges are transferred primarily through two processes: contact and induction. For instance, in the Van de Graaff generator, electrons are 'sprayed' from the lower comb onto an insulating belt, similar to shoes gaining electrons while walking on a carpet. These electrons then transfer to a metallic sphere which distributes the electrons on its outer surface due to repulsion between like charges.
The process can be equated to walking across a carpet. As the shoes rub against the carpet, they pick up electrons due to the closer contact between different materials, which is enhanced by the rubbing motion. This excess of electrons is then transferred to a neutral object, such as a doorknob, often resulting in a small spark.
Other interesting static electricity effects can be demonstrated using the generator, such as hair standing on end when touching the charged dome, creating miniature lightning bolts, or causing conductive objects like aluminum muffin tins to fly off due to charge accumulation and repulsion.