Electric Current & Charge Flow — A/L Physics

Electric Current (I) The rate of flow of electric charge through a cross-section of a conductor. Current is the flow of charge, not the charge itself. In a metal wire, free electrons drift slowly (mm/s) under an electric field, but the current establishes at nearly the speed of light. Example: When you switch on a torch, the bulb lights instantly because the electric field propagates rapidly, even though individual electrons move very slowly.

Conventional Current vs. Electron Flow Conventional current flows from positive to negative terminal; electron flow is opposite. By historical convention, current direction is taken as the direction positive charges would move. In metals, negative electrons actually drift from negative to positive. For circuit analysis, always use conventional current (positive to negative) — it works consistently with Kirchhoff’s laws and all standard formulas.