Introduction to Electricity

7SCIENCE

Electricity brainstorm

What is electricity?

• Electricity is matter and we know all matter is made of:– atoms

• Atoms are made of even smaller particles called electrons and protons

• These have an electric charge– Electrons = negative– Protons = positive

Electric charges

• Usually atoms have the same number of protons and electrons so the positive and negative charges are balanced– Sometimes atoms gain or lose an

electron• Gain = negative (adding negative!)• Lose = positive (taking away negative!)

• These electrons can move between objects and build up– Ex. Rubbing a balloon on your hair– Building up of electric charge is called static

charge

Electric forces

• Charged objects have an electric force

• Electric force can be:– Attractive– Repulsive

• Rule: objects with the same type of charge repel each other and those with unlike charges attract

ex. + and + = repel ex. + and - = attract

Insulators and Conductors

• Materials that don’t allow electrons to move easily from one surface to another is called an insulator– Ex. Plastic, wood, rubber

• Materials that allow electrons to move through them easily are called conductors– Ex. Metal wires: copper, silver, iron

• Why are electrical wires covered in plastic/rubber coating?

• Do you think your body is an insulator or conductor?