Static charge

When certain insulating materials are rubbed against each other they become electrically charged. Negatively charged electrons are rubbed off one material and on to the other. The material that gains electrons becomes negatively charged. The material that loses electrons is left with an equal positive charge.

When two electrically charged objects are brought close together they exert a force on each other. Two objects that carry the same type of charge repel. Two objects that carry different types of charge attract. Attraction and repulsion between two charged objects are examples of non-contact force.

Students should be able to:
- describe the production of static electricity, and sparking, by rubbing surfaces
- describe evidence that charged objects exert forces of attraction or repulsion on one another when not in contact
- explain how the transfer of electrons between objects can explain the phenomena of static electricity.

Electric fields

A charged object creates an electric field around itself. The electric field is strongest close to the charged object. The further away from the charged object, the weaker the field.

A second charged object placed in the field experiences a force. The force gets stronger as the distance between the objects decreases.

Students should be able to:
- draw the electric field pattern for an isolated charged sphere
- explain the concept of an electric field
- explain how the concept of an electric field helps to explain the non-contact force between charged objects as well as other electrostatic phenomena such as sparking.