Name: _(Write your name here)______________
LIGHT BULB WORKSHEET
Conserving the amount of energy we use is often suggested as an important way people can combat
things like acid rain and global warming. It is also an excellent way to combat the high cost of living.
The use of Compact Fluorescent Light (CFL) bulbs is often touted as one way to cut energy use. These
bulbs are not the strip lights you have seen in school building and stores. CFL bulbs are the size of a
normal light bulb but look like a twisted white rod instead of a glass globe.
To find out the impact the choice of bulb has on the amount of electricity we use save this worksheet to
your computer as a Word Document. The complete the following activity noting that you will post
some of the data to the Question and Answer forum on the class web site by Friday of this week.:
Visit Wal-Mart, Lowes, or ACE and find both of the following:
1. A box of normal (incandescent) soft white light bulbs. These must be 60W, medium base, soft
white bulbs. They may be general purpose or 2X (long life) bulbs. Make sure that they are
general lighting bulbs and not 3 way, fan, or any other color bulbs.
2. A box of compact fluorescent bulbs that are the equivalent of 60W. Make sure that they are
general lighting bulbs and not 3 way, fan, or dimmable bulbs.
The CFL bulbs will look like this:
The normal light bulbs look like this:
You must find a CFL that produces the equivalent light of a 60 watt normal incandescent bulb.
Note that the life of some bulbs is given as “year life”. For example 1.4 year life.
Each “year life” is equivalent to 3 hours per day for 365 days. 3 x 365 = 1095 hours. So, to convert
“year life” into hours you will need to do the following: year life x 1095 = life of the bulb in hours.
Once you have found your 2 boxes of bulbs you do not need to buy them.
Take 2 photos with each item; One showing you with the item, and one close enough so that it
shows the price and the information shown on its box. Attach (paste/insert them into the Word
document) the photos to the end of this worksheet.
Read the light bulb box and use the information provided to complete the table on the next pages.
Name: ___________________________________
LIGHT BULB WORKSHEET RESULTS
SHOW ALL CALCULATIONS
A Price of one 60 Watt normal incandescent light bulb (not the pack
just one bulb!) .
(Bulb chosen is Halco
6321-60 Watt-A19Frosted-5000 Life Hours510 Lumens-130 Volt-4
Pack) The price for the 4
Pack is given below.
=$1.92/4
=$0.48 per bulb.
B
Life time of the bulb in hours. Convert life in years to life in hours
if needed. Ask me for help if you have not procrastinated
C
Price of one Compact Fluorescent Light bulb (CFL)
4.6yrs X 3hrs per day X
365 days a yr.
Total=5037 hrs
(chosen bulb is
SYLVANIA 15-Pack 60Watt 4,100K Cool White
Fluorescent Tube Light
Bulbs (Common: 94-in;
Actual: 94.00-in).



D
Life time of the CFL bulb in hours. Convert life in years to life in
hours if needed. See me for help if you have not procrastinated
E
How many normal bulbs would you have to buy to cover the life of
one CFL bulb?
F
The Total cost of all the normal bulbs calculated in E would be?
G
The total cost of the one CFL was
H
Watts (electricity) used by the CFL to produce equal light as the
60W normal bulb
Uses 60 watts for
3850 lumens of
brightness
Bulb life is 12000
hours or 11.0 years
at 3 hours a day
Single-pin most
commonly used in
8-ft T12 fluorescent
fixture
=$ 12.98/15
=$0.865
11yrs X 3hrs per day X
365 days a yr.
Total=12045 hrs
Total=12045/5037
=2.39
=3 bulbs
=$0.44X3
=$1.44
=$0.865
=59W
I
J
K
A 10 Watt bulb uses 5 more watts of electrical energy per hour than
a 5 watt bulb. How much more energy does the normal bulb use per
hour than the CFL?
Multiply the extra energy used (answer to I) by the total life in
hours for the CFL. This will give you the amount of energy saved
by using ONE CFL bulb in your home. Remember to show your
=5W X 12045hrs
work!
=60,225Wh
Number of light bulbs in your home. Include all rooms, bathroom
lights, lamps, fans, etc. but not strip lights. (Parents home)
=10-5
=5W
=59/$0.865
=68.21
=69 bulbs
L
Calculate the energy saved by changing all home light bulbs to
CFL’s (Make sure you show your calculations). Hint: You know
how much energy is saved by one bulb –look at J.
M
Electricity is sold in kW not W. Convert the energy saved above
from Wh to kWh (÷1000)
N
The cost of electricity is about $0.08 per kWh. Calculate the cost
of this saved electricity (answer to M). This is how much money
you would save, over the life of the bulbs, if you changed all of
your bulbs to CFL’s. Post this value to the Q&A forum by Friday
O
Calculate the class average for the amount of money saved if only
CFL bulbs were used in the home.
P
There are about 5,700 single family dwellings in Milledgeville.
Changing all of the bulbs in Milledgeville to CFL’s would save
how much in electricity costs?
Energy saved by normal
bulbs is 5W X 5037hrs
=25,185Wh
=25,185/1000
=25.185kWh.
= 25.185kWh X $0.08 per
kWh.
=$2.0148
=60,225Wh/1000
=60.225kWh X $0.08
=$4.818
=5700 X $2.0148
=$11,484.36
Name: ___________________________________
Q
=18,774 X $2.0148
=$37,825.855
There are about 18, 774 single family dwellings in Baldwin county.
Changing all of the bulbs in our county to CFL’s would save how
much in electricity costs?
Remember that we have only changed the light bulbs in the homes and yet look at all of the energy that
has been saved and the $ we are no longer spending. Energy conservation is by far the easiest and most
convenient way to reduce our energy consumption.
Attach your photos of the boxes of light bulbs here.