9.6 Insulators and Conductors In order to use electricity we need both insulators and conductors. Insulators An insulator is a substance which slows the free movement of electrons from atom to atom. Since insulators do not allow the free movement of electrons, they cause the build up of static charge on the surface. The electrostatic series shows us which insulators can build up a charge on their surface. Things like paint and wax cause charges to build up on our cars. Insulators are very important to use on electrical devices to keep us from being shocked.

Conductors A conductor is a substance in which electrons can move freely from one atom to another. Since conductors (like copper) allow the free movement (conduction) of electrons, a static charge can never build up. This is why you can polish a metal tap it doesn’t build up a static charge. Where does the charge go? Remember that taps are grounded so the charge is taken away through the pipes into the ground.

Static Electricity and Winter Static electricity is worse in the winter. Why? The cold air is drier then the rest of the year and contains few water molecules. Why is that important? Remember that humid air can : discharge an object. Dry air is an insulator and does not easily pick up the charges from our body. The static charges that build up on our clothes and body tend to stay.

Common Insulators and Conductors Good Fair Good Conductors Conductor Insulator Copper Carbon Fur Gold Human body Rubber Mercury Earth Wood Iron Water Vapour Paper