In physics we use conventional current to describe the flow of charge.
Conventional current is imagined to move from the positive end of a battery to the negative end.
However, in a metal wire the actual charge carriers are free electrons, and they move in the opposite direction – from the negative side to the positive side.
Think of it like a water pipe: the water (current) flows from the high‑pressure side (positive) to the low‑pressure side (negative), but the water molecules themselves are moving from the low‑pressure side to the high‑pressure side.
The electric current \$I\$ is defined as the rate of flow of charge \$Q\$:
\$I = \dfrac{Q}{t}\$
Where \$I\$ is in amperes (A), \$Q\$ in coulombs (C), and \$t\$ in seconds (s).
| Direction | Charge Carriers | Real Flow |
|---|---|---|
| Positive → Negative | Conventional current | ↔️ (imagined direction) |
| Negative → Positive | Free electrons (\$e^-\$) | ⚡ (actual electron flow) |
Tip: When marking, remember that the diagram will show conventional current (→) even though electrons actually move opposite.
Common Question: “If a battery is connected to a resistor, in which direction does the electron flow?”
Answer: From the negative terminal of the battery, through the resistor, to the positive terminal.