People developed an understanding of electricity gradually.  Many of the earliest ideas came from everyday experiences.  For example, if you scuff your feet while walking over a carpet, you can cause a charge to build up, which leads to a nasty shock when you touch a person or an object.

Have you ever used these effects to give yourself or someone else a shock?

Give John's a little shake and wait a moment. What do you notice happening to the electrons? Then take his finger and touch the door. Can you explain why this happens? If not, don't worry, by the end of the lesson you will be able to.


Read Electrical Interactions
Read the information found on the bottom half of page 512 and the top half of page 513.  The information outlines the contributions of Benjamin Franklin and others to the study of electricity.

Identify the two types of electric charges.

One type of electric charge is positive, while the other type is negative.


Refer to the " info BIT" on page 513 of your textbook. Suggest a reason why doctors and nurses wear special slippers while working with patients receiving oxygen.

Since oxygen is an essential reactant for combustion, even the tiniest sparks around patients who are receiving oxygen could create a significant fire hazard. The special slippers prevent the buildup of an electric charge, which could produce sparks that could start a fire.







The video "Science World Resources: Electricity" shows how a Van de Graff generator can be used to show the repulsion of like charges.

Can you explain why the aluminum pie plates were able to 'float' off the Van de Graff generator? Would the same thing happen if plastic plates were used? Why or why not? 


Read The Modern Theory of Electrostatics
To learn why electrical cables are built from copper and plastic, read "The Modern Theory of Electrostatics" on pages 513 and 514 of the text.

Look around at your surroundings.

  1. Identify two materials that are conductors. Describe the essential characteristic that makes these materials conductors.
  2. Identify two materials that are insulators. Describe the essential characteristic that makes these materials insulators.

  1. Answers will vary depending on your location. Typical examples of conductors might include a metal chair leg or the wires inside the cable of a pair of headphones. In all cases, conductors are metals in which the outermost or valence electrons are held loosely, enabling the material to conduct electricity. 

  2. Answers will vary depending on your location. Typical examples of insulators might include a cushion on a chair or the soles of a pair of shoes. In all cases, insulators are non-metals in which the electrons are bound tightly to the nucleus, preventing the material from being a good conductor of electricity.


Refer to subatomic structures to explain why electrical cables are often made with a core of copper wire surrounded by a protective plastic coating.

The outermost electrons in copper atoms are free to move, which makes copper a good conductor.  The copper core allows electricity to travel down the centre of the cable. The outermost electrons in the atoms that form plastics are tightly bound to the nucleus and are not free to move, making plastic a good insulator. The plastic coating prevents the electricity traveling through the core of the cable from passing to unintended places through the walls of the cable.