Transcript Electricity - Warren County Schools

Electricity
Basic Terms #1
Ampere – rate of electrical flow (volume of
electricity flowing)
Sometimes referred to as amps
Voltage or electromagnetic force
– a measure of electrical pressure
Also abbreviated EMF or E
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
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)
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
Set of guidelines for use when designing
and installing electrical service and
devices
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 are 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 = 120*5
W = 600
W=V*A
Also means that:
V = W / A (watts divided by amps)
A = W / V (watts divided by volts)
Calculating Amps
Calculate the amperage of a 600 watt light
bulb that is running on a 120 volt circuit.
A= 600/120 or
5 amps
Calculate Voltage
What is the voltage on a circuit that has a
600 watt bulb that is pulling 5 amps.
V=W/A
Voltage = 600/5
120 volts