Discharge

When an object loses its charge we say it has . This happens when electrons are able to . They will continue to until the objects become equally charged. This means we now have potential difference () between objects.

The greater the charge on an isolated object the the voltage (p.d.) between the and . If the voltage becomes high enough, a (spark) may jump from the object to an earthed .

Metals are good conductors because of their structure. Metallic structures have the nuclei fixed in a lattice/matrix. Most of the electrons stay with their nucleus but the electrons in outer shells form a 'sea of electrons' able to move between the different nuclei.

Because they each other, they are generally evenly distributed throughout the material. When there is an average movement of this 'sea' in one direction we have flowing.

Different metals have different numbers of free electrons. The more free electrons in a material, the a conductor it is. We would say that it has a high conductance or a low resistance. Objects that do not have 'free electrons' are unable to conduct electricity and are known as .

Current can be thought of the number electrons passing a point in a circuit, in a bit of time. This rate of flow of electrical charge is called the current.

Find out more in the Electical Power Topic