What happens when an electric current passes through a wire?

When an electric current passes through a wire, it involves the movement of electric charge carriers, usually electrons, within the wire. The flow of electric current is a result of the movement of these charged particles in response to an electric potential difference (voltage) applied across the wire.

Here's a breakdown of what happens:

1. Voltage Source: An electric potential difference (voltage) is applied across the ends of the wire, creating an electric field.
2. Electron Movement: Electrons, which are negatively charged, move in response to this electric field. In metallic conductors like copper, which is commonly used in wires, electrons are the charge carriers.
3. Drift Velocity: Electrons do not move at a constant high speed; rather, they experience collisions with atoms and other electrons in the wire. This results in a net slow movement in the direction of the electric field, known as drift velocity.
4. Heat Generation: The collisions between electrons and atoms in the wire lead to resistance. As electrons overcome this resistance, some of their kinetic energy is converted into heat. This phenomenon is described by Joule's law, and it's the reason why wires can get warm when current flows through them.
5. Circuit Completion: The electric current completes a circuit, flowing from the negative terminal of the voltage source, through the wire and other components, and back to the positive terminal of the source.