Can be used to clarify several important concepts, such as:
- Charged particles exist in the wire before the current starts to flow
- Charged particles in complete circuits move at finite, observable speed - not the speed of light.
- When voltage is applied to a complete circuit, particles at all points in the circuit begin moving instantaneously and simultaneously.
- Charged particles in complete circuits can flow in a single direction (direct current) or back and forth (alternating current).