Electric Current Direction: Conventional Flow and Electron Motion

Direction of Electric Current

If you consider the position of a compass needle around a conductor carrying an electric current, you can establish a relationship between the direction of the current and the resulting magnetic field.

Please note the following: Electricity flows due to the movement of electrons through the conductor. Even before the existence of electrons was discovered, the flow direction of the stream was established. It was agreed that the current runs from the positive terminal of a power source to the negative terminal. (The conventional sense of the current is opposite to the actual motion of electrons; we use the conventional sense of the current in analysis.)

Indication of Current Direction in Diagrams

To characterize the direction of current flow in a drawing, two symbols are commonly used:

• An arrow pointing in the direction of the current flow.
• When looking at the direction of current flow, the stabilizing fins (tail) of the arrow are represented schematically by a cross (X).

If you look in the opposite direction of current flow, this is represented by a dot (.). The figure below shows the characterization of the direction of flow, using the example of current drivers (sources/sinks).

Relating Current to Magnetic Fields

If you examine the position of a compass needle around a conductor carrying an electric current, one obtains a relationship between the direction of the current and the magnetic field generated.

Remember: Electricity flows as electrons move through the conductor. The established convention for current flow runs from the positive terminal of a power source to the negative terminal. This conventional sense is opposite to the actual motion of electrons.

Diagrammatic Current Representation

To characterize the direction of current flow in schematics, two symbols are used:

When viewing the direction of current flow:

1. The tip of the arrow indicates the current direction.
2. The tail of the arrow is schematically represented by a cross (X).

Conversely, when viewing the current flow from the opposite direction, it is represented by a dot (.).