Electricity Notes

What is electricity?

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Electricity is the flow/movement of charges/electrons

Electricity always takes the quickest path with least resistance��How Electricity flows through something depends on whether it is a conductor or an insulator �

• Conductor- Electricity flows through easily- gold, copper, aluminum
• Insulator- Electricity does not flow through easily- rubber, plastic, wood, glass

AC vs. DC

• AC- Alternating Current
• Plugs in your house outlet
• Electrons go back and forth in small movements

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• DC- Direct Current
• Anything that uses batteries
• Objects that plug into the wall that have big boxes attached to the plug
• Electrons move in one direction through the whole circuit

Circuits

• Parallel

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• Series

Characteristics of Electricity (3)

• Voltage (V)(volts): voltage can be thought of as electrical pressure, it is the force that causes electrical charge to move or flow through a system. The Push or Pressure behind each electron
• Current (I)(amps): electric current is measured in amperes, and is defined as the rate at which electric charge travels through a conductor. The Speed that the electrons are moving at

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Characteristics of Electricity

• Resistance (R)(ohms): the rate at which electricity flows through a circuit. Increased resistance results in a decrease in the amount of current that will flow through the wire. Light bulb filament uses resistance to make light.

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• 4 factors affect resistance
• Material of wire
• length of wire
• area of cross section of wire
• temperature of wire

Ohm’s Law

• Mathematical formula that is used to describe the relationship between voltage (V), current (I), and resistance (R). Ohm's law can be written as follows:
• I = V / R
• V= I x R
• R= V / I

Electricity when compared to water/river

• Volts/Voltage- pressure of the water, how much water in river
• Amps/Current- flow of the river, how fast is it going
• Resistance/Ohms- width of the river, the bigger it is, the easier the water can flow

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• Wide river with lots of water moving very fast=
• Narrow river with little water moving very slow=
• Wide river with lots of water moving very slow=
• Narrow river with little water moving very fast=

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Electricity compared to vehicles

• High voltage- Large Semi-trucks
• Low voltage- small cars
• High Current- vehicles driving fast
• Low Current- vehicles driving slow
• High resistance- Vehicles driving on a narrow dirt road
• Low resistance- Vehicles traveling on freeway

Electrical Power(Watts)

• Power = current x voltage
• Watts = amps x volts
• W = I x V
• I = W / V
• V = W / I

Calculate the cost

• Kilo = 1000
• Kilowatt = 1000 watts
• Kilowatt-hour = 1000 watts power used for one hour
• Kilowatt-hour costs about $0.09
• A microwave uses 1000 watts, if you ran the microwave for 1 hour it would cost 9 cents.