Which electrical concept involves the imbalance of electrons between two bodies?

The concept that involves the imbalance of electrons between two bodies is static electricity. Static electricity occurs when there is an accumulation of electric charge on the surface of objects, which happens due to the transfer of electrons. This imbalance creates a difference in electric potential, and it isn't in motion as current electricity is.

When two different materials come into contact and are then separated, electrons can be transferred from one material to another, resulting in one object having an excess of electrons (negatively charged) and the other having a deficiency (positively charged). This charge imbalances can lead to phenomena such as sparks or static cling when the charged bodies come close together.

In contrast, current electricity refers to the flow of electrons in a conductive pathway, magnetism refers to forces related to magnets and magnetic fields, and voltage is the potential difference in electrical charge that drives current flow. These concepts are related to electricity and electromagnetism, but do not specifically describe the condition of electron imbalance as effectively as static electricity does.