In an electric circuit, the direction of current flow is defined as the direction in which positive charges would move. This convention was established historically before the discovery of the nature of electron flow, so it might seem counterintuitive since electrons are the actual charge carriers in most materials.
According to the conventional current flow convention:
Current Flow in a Closed Circuit: In a closed circuit, when a voltage source (like a battery) is connected, the positive terminal of the voltage source is considered the "higher potential" end, and the negative terminal is considered the "lower potential" end. Consequently, current flows from the higher potential to the lower potential, or from the positive terminal to the negative terminal.
Electron Flow: In reality, the charge carriers in most materials are electrons, which have a negative charge. Electrons move from the lower potential to the higher potential, which is the opposite direction of conventional current flow. So, electrons move from the negative terminal of the voltage source to the positive terminal.
It's important to note that in most practical cases, the direction of current flow doesn't affect the operation of the circuit or the calculations involved. The convention was established for consistency and ease of understanding, and it has been maintained for historical reasons.
In summary, in an electric circuit, current is considered to flow from the positive terminal of a voltage source to the negative terminal, even though electrons (the actual charge carriers) move in the opposite direction, from the negative to the positive terminal.