Electrical Efficiency

1
Electrical Efficiency LG to
understand how energy efficiency is calculated
use it to determine energy efficiency of
household electrical devices
2
Electrical Efficiency Electrical Power the rate
at which electrical energy is produced or
used. -measured in Watts (W) -one Watt is equal
to one Joule of energy used per
second LG to understand how energy
efficiency is calculated use it to determine
energy efficiency of household electrical devices
3
Electrical Efficiency Electrical Power the rate
at which electrical energy is produced or
used. -measured in Watts (W) -one Watt is equal
to one Joule of energy used per second e.g. 100
W light bulb uses four times as much energy per
second as a 25 W bulb. LG to understand how
energy efficiency is calculated use it to
determine energy efficiency of household
electrical devices
4
Electrical Efficiency kilowatt-hour (kWh) the
SI unit for measuring electrical energy usage -1
kWh is the use of one killowatt of energy for
one hour -3 600 000 times as much energy as 1
Joule LG to understand how energy
efficiency is calculated use it to determine
energy efficiency of household electrical devices
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Electrical Efficiency LG to
understand how energy efficiency is calculated
use it to determine energy efficiency of
household electrical devices
6
Electrical Efficiency Efficiency comparison of
the energy output of a device with the energy
supplied e.g. Clothes dryers -older clothes
dryer uses 800 kWh per year -new clothes dryer
uses 300 kWh per year -they both do the same
job so the new dryer is more than twice as
efficient LG to understand how energy
efficiency is calculated use it to determine
energy efficiency of household electrical devices
7
Electrical Efficiency Calculating efficiency of
a Device percent efficiency energy out x
100 energy in LG to understand
how energy efficiency is calculated use it to
determine energy efficiency of household
electrical devices
8
Electrical Efficiency Calculating efficiency of
a Device percent efficiency energy out x
100 energy in short form LG
to understand how energy efficiency is calculated
use it to determine energy efficiency of
household electrical devices
Eout efficiency _____ x 100 Ein
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Electrical Efficiency Example A light bulb uses
100 J of energy and produces 35 J of light
energy. Calculate the energy efficiency of the
light bulb. LG to understand how energy
efficiency is calculated use it to determine
energy efficiency of household electrical devices
10
Electrical Efficiency Example A light bulb uses
100 J of energy and produces 35 J of light
energy. Calculate the energy efficiency of the
light bulb. Given Eout 35 J Ein 100
J Unknown efficiency LG to understand
how energy efficiency is calculated use it to
determine energy efficiency of household
electrical devices
11
Electrical Efficiency Example A light bulb uses
100 J of energy and produces 35 J of light
energy. Calculate the energy efficiency of the
light bulb. Given Eout 35 J Ein 100
J Unknown efficiency
Eout Select efficiency _____ x 100
Ein LG to understand
how energy efficiency is calculated use it to
determine energy efficiency of household
electrical devices
12
Electrical Efficiency Example A light bulb uses
100 J of energy and produces 35 J of light
energy. Calculate the energy efficiency of the
light bulb. Eout Select efficiency
_____ x 100
Ein Solve efficiency 35 J x 100
100 J 35 LG to understand how
energy efficiency is calculated use it to
determine energy efficiency of household
electrical devices
13
Electrical Efficiency Try this A toaster oven
uses 1200 J of energy to produce 850 J of thermal
energy. Calculate the efficiency of the toaster
oven. LG to understand how energy
efficiency is calculated use it to determine
energy efficiency of household electrical devices
14
Electrical Efficiency Try this A toaster oven
uses 1200 J of energy to produce 850 J of thermal
energy. Calculate the efficiency of the toaster
oven. Given Eout 850 J Ein 1200
J Unknown efficiency Select
Eout efficiency _____ x 100
Ein LG to understand how
energy efficiency is calculated use it to
determine energy efficiency of household
electrical devices
15
Electrical Efficiency Try this A toaster oven
uses 1200 J of energy to produce 850 J of thermal
energy. Calculate the efficiency of the toaster
oven. Solve efficiency 850 J x 100
1200 J
71 therefor the toaster oven is 71
efficient LG to understand how energy
efficiency is calculated use it to determine
energy efficiency of household electrical devices
16
Electrical Efficiency Cost of Operating
Electrical Devices LG to understand
how energy efficiency is calculated use it to
determine energy efficiency of household
electrical devices
cost to operate power x time x cost of used electricity
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Electrical Efficiency Example a laptop computer
uses a 75 W adapter when it is plugged in.
Electricity costs 5.6/kWh. Calculate how much
it would cost to operate the laptop for 1 year
for 24 hours per day. LG to understand
how energy efficiency is calculated use it to
determine energy efficiency of household
electrical devices
18
Electrical Efficiency Example a laptop computer
uses a 75 W adapter when it is plugged in.
Electricity costs 5.6/kWh. Calculate how much
it would cost to operate the laptop for 1 year
for 24 hours per day. Given power 75
W 0.075 kW LG to understand how
energy efficiency is calculated use it to
determine energy efficiency of household
electrical devices
19
Electrical Efficiency Example a laptop computer
uses a 75 W adapter when it is plugged in.
Electricity costs 5.6/kWh. Calculate how much
it would cost to operate the laptop for 1 year
for 24 hours per day. Given power 75
W 0.075 kW time 24 hours per day for
365 days 8760 hours cost
5.6/kW?h LG to understand how energy
efficiency is calculated use it to determine
energy efficiency of household electrical devices
20
Electrical Efficiency Example a laptop computer
uses a 75 W adapter when it is plugged in.
Electricity costs 5.6/kWh. Calculate how much
it would cost to operate the laptop for 1 year
for 24 hours per day. Unknown cost to
operate Select cost to operate power x time x
cost of
used electricity LG to
understand how energy efficiency is calculated
use it to determine energy efficiency of
household electrical devices
21
Electrical Efficiency Example a laptop computer
uses a 75 W adapter when it is plugged in.
Electricity costs 5.6/kWh. Calculate how much
it would cost to operate the laptop for 1 year
for 24 hours per day. Unknown cost to
operate Select cost to operate power x time x
cost of
used electricity Solve cost
to operate 0.075 x 8760 x 5.6 3679
(36.79) LG to understand how energy efficiency
is calculated use it to determine energy
efficiency of household electrical devices
22
Electrical Efficiency Example a laptop computer
uses a 75 W adapter when it is plugged in.
Electricity costs 5.6/kWh. Calculate how much
it would cost to operate the laptop for 1 year
for 24 hours per day. Unknown cost to
operate Select cost to operate power x time x
cost of
used electricity Solve cost
to operate 0.075 x 8760 x 5.6 3679
(36.79) LG to understand how energy efficiency
is calculated use it to determine energy
efficiency of household electrical devices
23
Electrical Efficiency Try this Calculate the
cost of operating a 1500W hair dryer to dry your
hair for 6 minutes per day for 3 days. The cost
of electricity is 5.6/kWh LG
to understand how energy efficiency is calculated
use it to determine energy efficiency of
household electrical devices
24
Electrical Efficiency Try this Calculate the
cost of operating a 1500W hair dryer to dry your
hair for 6 minutes per day for 3 days. The cost
of electricity is 5.6/kWh Given power 1500
W 1.500 kW time 6 minutes per day
for 3 days 6 min x 3 18 min 0.30
hours cost 5.6/kW?h Unknown cost to
operate LG to understand how energy
efficiency is calculated use it to determine
energy efficiency of household electrical devices
25
Electrical Efficiency Try this Calculate the
cost of operating a 1500W hair dryer to dry your
hair for 6 minutes per day for 3 days. The cost
of electricity is 5.6/kWh Select cost to
operate power x time x cost of
used
electricity Solve cost to operate 1.500 x
0.30 x 5.6 2.52 LG to
understand how energy efficiency is calculated
use it to determine energy efficiency of
household electrical devices