How do Van de Graff generators obtain their electrons?

Van de Graaff generators operate based on electrostatic principles, specifically the process of charge generation and transfer. They utilize a moving belt made of insulating material that picks up electrons from a grounded source as it moves through the generator. These electrons are then transported up to the dome of the generator, where they accumulate and create a high-voltage electric charge due to the separation of charges. The accumulation of these electrons on the surface of the dome results in a significant electrostatic potential, which is the primary function of the Van de Graaff generator.

Understanding that the generator relies on electrostatic principles is crucial since it highlights the fundamental physics behind how these devices generate high voltages. This principle differs from the inaccurate depictions in the other options, which suggest mechanisms that do not align with the actual operation of a Van de Graaff generator.