ASNT Industrial Radiography Radiation Safety Practice Test

What fundamental principle underlies the operation of a Van de Graaff generator?

1. Thermodynamic expansion

2. Electromagnetic induction

3. Electrostatic principle

4. Nuclear decay

The correct answer is: Electrostatic principle

The operation of a Van de Graaff generator is fundamentally based on the electrostatic principle. This device generates high voltages by moving electric charge to a conductive sphere at the top of the generator. The sphere accumulates a large number of positive charges, which can be utilized in various applications, such as particle accelerators or experiments in nuclear physics. The electrostatic principle is central because it involves the interaction of electric charges. The Van de Graaff generator utilizes a moving belt that transports charge from the base to the top of the sphere. The mechanism relies on the concept that unlike charges attract and like charges repel; thus, as charge accumulates on the sphere, it creates an electric field that can accelerate particles. In contrast, thermodynamic expansion pertains to the behavior of gases and heat transfer, and it does not play a role in the functioning of a Van de Graaff generator. Electromagnetic induction involves generating electric currents through changing magnetic fields, which is not applicable to this device. Nuclear decay relates to the process by which unstable atomic nuclei lose energy by radiation, which is separate from the processes involved in electrostatics.