Conductors, insulators, electric current

An electric current is a flow of charge. In metal wires, the charges are carried by very small particles called electrons.

Electrons flow easily through metals, therefore we describe them as being good conductors.

A very poor conductor is known as an insulator.

In metals, some electrons are free to move between atoms. The number of electrons flowing one direction is roughly equal to the number flowing in the opposite direction. There is, therefore, no overall charge.

If a cell or battery is connected across the conductor, more of the electrons flow in a direction away from the negative terminal and towards the positive charge than in the opposite direction. There is now a 'net flow charge'. This is what we call an electric current.