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Goal: To illustrate the efficiency of different types of lighting in relationship to cost and light output.
Objectives: Students will:
- Analyze energy efficiency in lighting
- Determine cost vs. light output
Materials (for a class of 30):
- Class set of Watts Up devices (approximately $100/device) with instruction sheets -about 8 (http://www.doubleed.com)
- Class set of light meters
- Class set of rulers
- 8 light bulbs (different wattages and types)
- Power supply and bulb sockets for each group
- Graph paper
- Large classroom timer with stop alarm
- Class set of Student Sheets
Time: 45 minutes
Standards Met: S6, M1, M2, M3, M4, M7, M12
Procedure:
PREP
- Set up 8 stations in the classroom. Each station should have a power supply, a Watts Up meter, one type of light "bulb," and a light meter.
- Following the instructions on the Watts Up instruction booklet, program into the meter the cost per kilowatt-hour for your area of the country. (You can get this information from a standard electrical bill.)
IN CLASS
- Divide the class into groups of four.
- Go through the basic operation of the Watts Up meter with your students.
- Explain to the students that each station will time for exactly five minutes.
- During that time, each group will record the type of "bulb" and read its light intensity at a distance of 30 cm. Every minute they will also record the wattage used and the cumulative cost (both are programmed into the device).
- They are to record this information in Table 1 of their Student Sheets. After 5 minutes, have the students rotate to a different station.
- When all the stations have been covered, or until time runs out, have the students turn off all electrical devices.
- The students are now to graph their results on the graph paper you give them.
- Have one member of the group graph cost vs. time for each station visited, another, type of bulb vs. light output, and a third, wattage vs. time for each station. The fourth individual of the group should decide what other two variables they could compare, and graph them.
- Once all the equipment has been returned to the proper location, have the students answer the Questions for Thought on the Student Sheet.
Follow up Activity
Have the students ask their parents to show and explain to them their home electric bill over the last several months. Have each student then design and implement an experiment that might reduce his or her electric bill. They are allowed to change only one variable within their electrical use (example, don't use any hairdryers). After the student have done their experiment for a two-month period, have them graph and report their results to the class.
Student Data Table 1
Name: ___________________________________________ Period: ____________________
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