English: Diagram showing the direction of current flow in an electric power source such as a battery or electric generator or other active component. In a power source the electric current i flows into the negative terminal and out of the positive terminal. The electric charges are forced to move in the opposite direction to the electric field E, in the direction of increasing electric potential gradient. Work must be done on the charges to make them move in this direction. The potential energy of the charges (color) is increased, so electric power p < 0 flows out of the component into the circuit. Therefore the component must have a source of power (yellow arrows).

In contrast, in an electrical load such as a light bulb or electric motor or other passive component, the current flows into the positive terminal and out of the negative terminal, in the direction of lower potential energy. So work is done by the charges on the component and power flows out of the circuit into the component. A companion load animation is located at Electric load animation.gif.