Comparing light bulbs STEM energy activity

Choosing light bulbs for your home has changed so much in the last ten years. How do you decide what’s best? Here’s an experiment children can do comparing light bulbs. Which makes the most sense for the family?

Congress passed a law in 2007 that phases out the US production of incandescent bulbs. The old-style tungsten-filament bulbs do not meet new energy standards. Incandescent, CFL (compact fluorescent), and LED bulbs are all available for our standard American light sockets. To do a comparison and analysis, we need to know

• the power used in watts,
• the brightness in lumens,
• the price of the bulb,
• life of bulb,
• the price of power in kilowatt-hours.

The bulb package will show what incandescent equivalent is in watts and also the estimated life of the bulb in hours. Be sure to save the packages for this experiment.

I recommend using 40-watt incandescent bulbs and the equivalent. If all the bulbs are close to equivalent in brightness, that will make the comparison easier to understand. A 40-watt incandescent bulb should give about 450 lumens in brightness.

There are gadgets on the market that we can use to measure the power being used by our appliances. One is the Kill-A-Watt Monitor. Along with this experiment, you can use this device to measure power use around the house, such as: coffee maker with hot water reservoir; microwave; TV; computers and printers; cell phone recharging; and video games.

Update (04.21.15): I was fortunate to meet last week with the researchers from University of North Texas. They have a great project for middle school children called Going Green! Middle Schoolers out to Save the World . They are using the Conserve Insight energy use monitor from Belkin. This device has a 5-foot cord between plug and monitor, allowing use in more spots around the home. The buttons on the monitor will show estimated carbon dioxide emissions from the plugged-in device, or operating cost, or watts. The user guide gives clear instructions for changing the settings to enter the kWh rate from your power bill.

Safety note: Be sure to explain safety precautions to children. This experiment uses electric plugs and glass light bulbs. The bulbs can become hot when lit, they are bright when looking directly at them, and they can easily break when being screwed in or out of the lamp base. Disclaimer: All information provided on this site is for entertainment purposes only. Using any information from thecasabouquet.com is at your own risk.

Instructions

Plug Kill-A-Watt Monitor into outlet on power strip. Plug bulb outlet into Kill-A-Watt Monitor.

Screw in

• Incandescent bulb
• CFL bulb (Be sure to hold the base NOT the glass while handling)
• LED bulb

(Note: this is easiest if you have 3 power strips, 3 Kill-A-Watt Monitors, and 3 bulb outlets. Instead of the bulb outlets, you could also 3 small lamps.

Otherwise, be extremely cautious about changing the light bulbs. Incandescent bulbs get extremely hot and CFL bulbs easily shatter if not handled by the bottom.)

Press Watt button on the Kill-A-Watt to view how many watts are used with each bulb.

Note differences. Which bulb saves you money on your power bill? The power company bills based on kilowatt-hours. (US average is 12 cents/kWh; look up the average for your state). Is there a difference in the amount of heat each bulb makes?

You can use the KWH/Hour button to switch views of the time elapsed and the cumulative energy consumed.

Look at the packages for each bulb. How much does each one cost? How many hours is each estimated to last? How many hours each day would you use each bulb? Calculate how many days each bulb might last in your home.

Compare the brightness and color of the bulbs. You can use a photographer’s light meter or a Vernier LabQuest and light sensor to measure the brightness. (Note: Indoor lighting ranges from 100 – 1000 lux. 1 lux = 1 lumen/m²). Point the sensor at a paper illuminated by the bulb.

Ask the children to design lighting for different rooms. What type of lighting is needed for watching TV or playing a game? What type is needed for reading or homework? For makeup and grooming in the bathroom? For the kitchen?

Supplies for comparing light bulbs

• 40-watt equivalent light bulbs: incandescent, CFL, LED (keep packages and make note of the prices)
• Kill-A-Watt monitor (or Belkin Conserve Insight)
• Outlet to lampholder adapter
• Power strip with on/off switch
• Light meter (optional)
• Paper or notebook for recording results, pen

Sources

Affiliate links: if you make a purchase using these links, I’ll receive a small compensation towards maintaining this blog.
P3 P4400 Kill A Watt Electricity Usage Monitor
Belkin 6-Outlet Surge Protector with 2 ft. Cord (2-Pack)
Leviton 61 660 Watt, 125 Volt, Polarized Outlet-to-Lampholder Adapter, Brown
40-Watt incandescent Light Bulb 
Philips 433201 40 Watt Equivalent SlimStyle A19 LED Light Bulb Soft White, Dimmable
EcoSmart 9 Watt Soft White Compact Fluorescent (CFL) Light Bulbs 4-Pack, 40 Watt Equivalent, 550 Lumens

What is the science?

Content: Energy, electromagnetic radiation, light, electricity, analyzing and interpreting data, incandescence, fluorescence, semiconductors

Thomas Edison and his team invented the incandescent bulb in 1879. Edison used a carbon-coated bamboo filament that was heated to high temperature to give off light. Modern incandescent bulbs use tungsten. CFLs contain a gas that is excited by electricity to give off light through fluorescence. LEDs use two semiconductor materials to exchange electrons, similar to silicon chip technology. The US government calculates that if one 60-watt incandescent bulb in every home was replaced by an equivalent CFL bulb, in one year greenhouse gas emissions would be saved equal to 550,000 cars.

Resource Links

• http://science.howstuffworks.com/environmental/green-tech/sustainable/led-light-bulb.htmks
  • LED light bulb explanation from How Stuff Works
• http://www.energystar.gov/index.cfm?c=cfls.pr_cfls_lumens
  • Incandescent watts brightness in lumens from Energy Star
• http://www.eia.gov/electricity/monthly/epm_table_grapher.cfm?t=epmt_5_6_a
  • Average price of electricity from the US Energy Information Administration
• http://www.need.org/energysources
  • Infobooks for various grade levels from the National Energy Education Development Project
• http://www.vernier.com/products/interfaces/labq2/
• • LabQuest2 from Vernier Software & Technology
• http://www.flinnsci.com/teacher-resources/safety/general-laboratory-safety/
  • General Lab Safety resources from Flinn Scientific. Be sure to check out the Student Safety Contract.

Let’s talk story

Why can’t school be more like summer camp? In my career as a university pre-college outreach professional, I had the opportunity to plan summer educational experiences for middle school and high school students. And I found that joy of learning still exists! By approaching lessons and units with the perspective of camp counselors, you can inject the wonder and motivation that so often disappears in our testing-crazy times.

Tutu is a name for a grandparent in Hawaii. When our grandson comes to spend time with us, we say he is at Camp Tutu! Welcome to Camp Tutu, my way of energizing science lessons!

Children love helping out with the family. How light bulbs work and their cost to the family is usually a very new subject to them. Comparing light bulbs, making measurements and doing math towards a purpose is very exciting. And the children love the idea of being an expert when they go to the store with their parents!

I’ll be looking for comments below, or contact me at lisa [at] casabouquet[dot]com.

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