Electric Current
Describe the movement of electric charges through a medium.
- Current is the rate at which charge passes through a cross-sectional area of a wire. Relevant equation:
- Electric charge moves in a circuit in response to an electric potential difference, sometimes referred to as electromotive force, or emf (ε).
- If the current is zero in a section of wire, the net motion of charge carriers in the wire is also zero, although individual charge carriers will not have zero speed.
- Although current is not a vector quantity, it does have a direction. The direction of current is associated with what the motion of positive charge would be but not with any coordinate system in space.
- The direction of conventional current is chosen to be the direction in which positive charge would move.
- In common circuits, current is actually due to the movement of electrons (negative charge carriers).