Conductors

Materials that permit electrons to flow freely from particle to particle are called conductors. The outermost electrons in the atoms of a conductor are loosely bound that they float in the space between atoms. These free electrons can be induced by an external force (voltage) and made to float in the same direction. When a voltage is applied to one end of the conductor, electrons start to flow in the same direction and the current flows in the opposite direction, as shown below.

    When there is no voltage across the conductor the electrons do not flow and there is no current, as shown below.

    The degree of conductivity depends on various factors, such as length, thickness, temperature and the type of material. For instance, glass is a good insulator at room temperature, but becomes a conductor when heated to high temperature.

    The following are a few examples for good conductors.

• Silver
• Copper
• Gold
• Aluminium
• Iron
• Steel
• Brass
• Bronze
• Mercury
• Graphite
• Dirty water
• Concrete