Electricity A Review and then some…

Ampere – rate of electrical flow (volume of electricity flowing) “Amps”

Voltage or electromagnetic force – a measure of electrical pressure – a measure of electrical pressure

Resistance The opposition to the flow of electrons through a conductor – measured in Ohms

Watt Refers to the amount of power derived from a device or the rate of doing work Example – 100 watt light bulb 1500 watt blow dryer 1500 watt blow dryer Kilowatt = 1000 watts

Kilo-watt hour Electricity is sold by the kilowatt hour (gasoline is sold by the gallon) Using 1000 (kilo) watts for one hour is a KWH

Watts and Horsepower 746 watts = one horsepower

Watts = Volts x Amps Sometime referred to as the West Virginia Formula. The amount of work that can be done in a circuit is equal to the voltage in the circuit times the amps

WVA Analagy You can wash your car (do work) faster is you have a large hose with lots of pressure. A large hose will allow for greater flow of water (flow = amps) Pressure would be = voltage (force)

Types of Electrical Current

 Alternating Current  The current that flows in cycles, traveling first One Direction (no pun intended), then reversing to the other direction, and so on.  Our AC is 60 cycles per second, also called 60 Hertz (Hz).  Current that changes direction 120 times per second.

 Alternating Current Examples  To the window… from the wall…

 Direct Current  The current in which electrons flow only in One Direction (again, no pun intended!).  Electrons flow from the negative terminal to the positive terminal in an electrical circuit.  Fixed polarity- direction of flow.

 Direct Current Examples…  From batteries…

Circuit A controlled path for electricity to flow beginning at the source (usually a breaker), traveling to the consumer (ex. light) and back to the source. The colored wire goes to the consumer and the white wire “comes back” to complete the circuit Unless a complete circuit is made – the devices will not work Breakers and switches are usually used to control the flow

National Electrical Code The benchmark for safe electrical design, installation, and inspection to protect people and property from electrical hazards. The NEC addresses the installation of electrical conductors, equipment, and raceways. Updated and published every three years.

Conductor Substance that will allow for the flow of electricity Most common: copper, aluminum Best Conductor: Gold

Insulator Substance that does not allow for the flow of electricity Plastic, rubber

Parallel Circuit A circuit that has more than one way that electricity can flow. Most common type of circuit

Series Circuit Has only one pathway for electricity to follow. If there is more than one device in the circuit, the electricity must flow through one device and continue on to the next device. Not normally used in houses. Christmas lights are sometimes wired in series. That is why if one bulb goes out the whole line goes out

W = V*A A device (such as a light) hooked to a 120 volt circuit that is pulling 5 amps would be using how many watts?

W = V * A Also means that: V = W / A (watts divided by amps) A = W / V (watts divided by volts)