Final answer:
Electrical currents created when two different metals come into contact are known as the thermoelectric effect or Seebeck effect. Other effects like the Hall effect also explain how currents are generated and relate to potential differences and voltage sources necessary for maintaining current.
Step-by-step explanation:
When two different metals come into contact and create an electrical current, the phenomenon is known as thermoelectric effect or Seebeck effect. This occurs because different metals have different electron densities, which causes a potential difference at the junction, leading to an electric current if the circuit is closed. Another related phenomenon that occurs when charges move through a conductor in a magnetic field is called the Hall effect, named after Edwin Hall. This is the creation of a voltage across a current-carrying conductor by a magnetic field.
All devices that create a potential difference such as batteries, generators, and wall outlets are referred to as voltage sources, which are necessary to maintain a current. The current that flows through substances is, according to Ohm's Law, directly proportional to the voltage applied. This relationship is vital in understanding how electrical currents are driven, how resistivity affects the flow, and diverse ways in which charges can move depending on the conducting material.