ELECTRICITY

Shoulder Partner Soon all cars, boats and airplanes will all run on electricity. Do you agree or disagree with this statement and why?

Electric Charge Protons and electrons both have the property of charge. Remember, 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.

Electric Field An electric field extends outward through space from every charged particle. As things move close to each other the charge can jump to another object.

Electricity Facts….

Table Talk Was electricity invented or discovered? What’s the difference between invention and discovery?

Static Electricity Charge is only 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.

Methods of Charging Friction – when two objects are rubbed together. Ex: balloon on your hair. Conduction –direct contact of objects. –Ex: 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. Ex: a negatively charged rubber rod can pick up tiny pieces of paper.

Electric Discharge Electric discharge – the loss of static electricity. Sometimes slow and quiet, or rapid with a spark of light, shock, or crackle of noise. Ex: lightning.

Lightning Safety!

Circuits A circuit –forms 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.

Face Partner How could you test to see if something conducts electricity? How could you test to see which conduct electricity better?

“Braniacs” on Electricity

Things to know… Georg Simon Ohm established the relationship between electric current and potential difference. Resistance – ( R ) opposition to the flow of electric charge –ex: copper has low: iron has high Ohm -the unit to measure resistance. Ohm’s law – the current in a wire is equal to the voltage divided by resistance or I = V/R

Superconductor Superconductor – a wire kept at extremely low temperatures, resistance is zero. High resistance… Low resistance If YOU were an electron…

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

Table Talk What is the electrical difference between a battery and an outlet? How are they also similar?

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

SOURCES Battery – converts chemical to electrical Photocell – converts light to electrical Thermocouple – converts heat to electrical Electric generator – converts mechanical to electrical. Geothermal – earth’s internal heat to electrical

Series vs Parallel

Series circuit – only one path to take; if any part goes out the whole thing goes out. Ex: old Christmas lights Parallel circuit – separate paths. Ex: circuits in homes. Fuses – protect against too much current flow Circuit breakers – similar to fuses but can not burn out.

Series vs Parallel Draw these…

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

Electric Safety (Do not need to write) 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 low and stay away from trees. Safest spot in a lightning storm is inside a car.

Electric Safety

Class Discussion What would happen if a storm knocked out the electricity in Virginia Beach and it couldn’t be restored for a month? What would the sequence of events be?

Lastly!