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?