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21.4
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Gravity
Terms in this set (13)
other source of energy
At power plants, steam form burring fossil fuels, nuclear reactions, wind, solar heating, and ocean tides
- Each source provides the energy of motion to the generators producing electrical energy.
Electric Power
Is the rate at which electrical energy is generating from another source of energy.
turbine (step 1 how the electric power is generated)
Falling water provides energy to turn the turbine of the generator.
shaft (step 2 how the electric power is generated)
the shaft turns a powerful electromagnet within a coil of wire generating electrical current
(step 3)how the electric power is generated
-Far from the power plant a step-down transformer reduce voltage so the current can be sent though smaller lines to neighborhoods.
-Another transformer reduces the voltage to the level it needed to operate lights and appliances.
How dies the power plant convert the energy of motion into electrical energy?
Very large generators in the plant hold powerful electromagic surrounded by massive coils of copper wire
electric Power
is the rate at which electrical energy,generated from another source of energy
- power refers to the rate at which device converts to electric energy, back into another form of energy such as LIGHT, HEAT, SOUND
Watt (W)
the unit for measurement for power is the watt (W)
watts measure the rate at which energy is used by an electric appliance
- power is measured by watts (power=watts)
kilowatt (KW)
kilowatt (KW) is a unit of power equal to one (thousand) 1,000 watts
The formula for power
electric power = voltage * current (P=VI)
voltage = current / electric power
current = voltage / electric power
I=CURRENT
calculating energy
energy use = power * time (E=PT)
power = time/energy use
time = power / energy use
kilowatt-hour (KWH)
kilowatt-hour (KWH) is the unit of measurement for energy usage
a kilowatt-hour (KWH) is equal to one kilowatt of power for a one hour period
MATH/SCIENCE
QUESTION: How much energy is used to dry clothes in a 3KW dryer for 30 minutes?
WHAT DO YOU KNOW: power=3.0 KW, time=0.5 hr
WHAT DO YOU WANT TO FIND OUT: energy used
WRITE THE FORMULA: e=pt
SUBSTITUTE INTO THE FORMULA: E=3.0 (KW) * 0.5 hr
CALCULATE AND SIMPLIFY: e= 1.5 KWh
CHECK THAT YOUR UNITS AGREE: units is KWh. unit for energy used is KWh. units agree
ANSWER: 1.5 KWh
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