What is caused by friction between small particles or contact and separation of two nonconductive substances?

The phenomenon caused by friction between small particles or the contact and separation of two nonconductive substances is known as static electricity. This occurs when two nonconductive materials come into contact, causing electrons to be transferred from one material to the other. As a result, one material becomes positively charged (loses electrons), while the other becomes negatively charged (gains electrons).

This process occurs because nonconductive materials do not allow charges to move freely, leading to the build-up of electrical charge in localized areas. The accumulated charge can lead to static electricity, which can manifest itself in various ways, such as sparks or attraction/repulsion between objects when they are brought close to each other.

Understanding static electricity is crucial because it can affect various systems and materials in electrical engineering and power production. In contrast, other options such as electromagnetism, which pertains to the interaction between electric currents and magnetic fields, conductivity, which refers to a material's ability to conduct electric current, and induced voltage, which is generated due to changing magnetic fields, do not directly relate to the friction and separation of nonconductive substances in the same manner.