Electrical conductivity of metals

For this light bulb to shine, it needs electric current, for instance, from a battery, and the current has to get from the battery to the lamp. So, we need something that can conduct electricity, like these copper wires. Now, current is flowing from the battery to the lamp and back again. The current consists of electrons moving through the wires. If we replace the copper wires with strips of aluminium, the lamp still shines.

And this works with steel wires and silver and gold wires, but that makes for a very expensive lamp. Whatever metal we use, the lamp will shine. All metals conduct electricity. Why is that? It has to do with the atoms of metals.

All atoms have an atomic nucleus surrounded by electrons in different electron shells. In a metal, atoms will let go of the electrons in their outermost shell. These released electrons move around throughout the metal in all directions. They are free electrons. Now, we’ll connect this piece of metal to a battery.

Let’s pause the motion of the electrons to show more clearly what happens. A battery has two ends – two poles. One is positive, the other negative. Here, at the negative pole, the battery sends more electrons into the metal wire. This gives an excess of electrons at this end, an excess of negative charge.

The electrons in the metal are pushed away, repelled by this negative charge. At the other end, the positive pole, the opposite happens. Here, the battery pulls electrons out of the metal. At this end, there will be a lack of electrons, a positive charge. This attracts the electrons within the metal wire.

So, the electrons in the metal are repelled by the negative pole and attracted to the positive pole. The electrons are constantly moving around in different directions colliding with each other and with the atoms. But when a battery is connected, they move a little bit more in this direction, away from the negative pole and towards the positive. The metal conducts electricity.