1. ELECTRICITY

2. Electric Charge  Protons and electrons both have the property of charge. Recall that protons are positive and electrons are negative.  A force of attraction exists between things that have opposite charges.  A force of repulsion exists between things that have same charges.

3. Electric Field  An electric field extends outward through space from every charged particle. As things move toward each other the charge may move from one object to another.  The electric field is strongest near the charged particle.

4. Static Electricity Because electrons can move freely things can become either positively or negatively charged. Charge is only being transferred from one object to another. This is called the Law of Conservation of Charge. Static electricity – is the buildup of electric charges on an object.

5. Methods of Charging  Friction – when two objects are rubbed together. Example: balloon on your hair.  Conduction – the direct contact of objects. Example: plugging something in.  Conductors – allow electricity to go through easily  Insulators – do not allow it to move through.  Induction – the jumping of electricity from one object to another. Example: a negatively charged rubber rod can pick up tiny pieces of paper.

6. Electric Discharge Electric discharge – the loss of static electricity as electric charges move off an object. Sometimes slow and quiet, or rapid with a spark of light, shock, or crackle of noise. Example: lightning or a simple static shock

7. Circuits  A circuit – is formed when a wire is connected to the terminals of a source forming a complete path.  Electric current – the amount of charge that passes a given point per unit of time.  The symbol for current is I

8. Things to know…  Georg Simon Ohm established the relationship between electric current and potential difference. Ex. 8 v battery vs 4 v battery.  Resistance – R opposition to the flow of electric charge (example: copper low: iron high) The unit to measure resistance is the ohm  Ohm’s law – the current in a wire is equal to the voltage divided by resistance I = V/R

9. Current direction  DC (direct current ) – electrons always flow in the same direction. Example: batteries  AC (alternating current) electrons move back and forth, reversing direction regularly. (example: current in home changes direction every second 120x)

10. Circuits  Electric circuit – consists of a source of energy; a load; wires, and a switch.  Sources: battery, thermocouple, photocell, or electric generator  Load – uses the electricity switch source load wire

11. Series vs Parallel  Series circuit – only one path to take; if any part goes out the whole thing goes out. Example: old Christmas lights  Parallel circuit – separate paths. Example: circuits in homes.  Fuses – protect against too much current flow, they burn out and can be a hassle  Circuit breakers – like fuses but do not burn out.  Take out packet & complete page 2 Electrical Currents

12. Series vs Parallel draw these

13. Power  Electric Power – a measure of the rate at which electricity does work or provides energy. Measured in watts.  Power = voltage x current  Energy = power x time

14. Electric Safety  Never handle when wet or near water  Never run wires under carpet  Never overload circuits  Repair worn out wires  Put nothing in electric sockets that does not belong  Never go by fallen wires or power lines  In lightning storms get down to the ground by crouching down and stay away from trees.  Safest spot in a lightning storm is inside a car.