Fun with Less Kilowatts: Build Your Own Light Bulb

By Vernon Trollinger, August 14, 2017, Events & Fun, Family

Welcome to Fun with Less Kilowatts! We believe that science experiments at home can be a creative way to engage kids in learning while having fun. They can be educational AND great activities to keep your kids busy and away from the television. Each month, we’ll feature a new science experiment that can be a great resource for parents and teachers.

Build Your Own Light Bulb

Compared to LEDs and CFLs, building your own incandescent light bulb is incredibly easy. Incandescent light bulbs work by heating a filament of wire suspended between two contacts. By using enough electrical current, the filament will heat up to the point that it begins to glow. The problem is that if you do this in the open air the filament will oxidize —or essentially burn up. That’s why incandescent bulbs have all the air sucked out of them when they are made.

Now, contrary to popular belief, Thomas Edison did not invent the light bulb. The light bulb wasn’t even first invented in America. The first electric light bulb was invented in 1841 in England where Frederick De Moleyns patented a glass bulb that used two platinum electrodes with powdered carbon set between them that would glow (or burn) due to strong electrical resistance. The device worked but gave feeble light due to only a partial vacuum seal on the bulb. By the time Edison arrived on the scene, some 22 other inventors either contributed to or held patents on a variety of light bulbs.

Edison and his staff tackled the incandescent light bulb problem in 1878. The challenge was to find the right kind of filament that would give off the most amount of light for the longest period and be dirt cheap. The bulb also had to be made so that there would be a very good and reliable vacuum seal. Edison tried a variety of filaments, including carbon, carbonized cotton thread, and ultimately carbonized bamboo which burned steadily for 1200 hours. This was the bulb Edison used when he lit up a street in Menlo Park on Dec 31, 1879. He finalized the patent for his lamp shortly afterwards in January, 1880. By 1906, he had improved his bulb’s design by changing the filament to tungsten wire. Tungsten filament bulbs basically remained unchanged for a century.

The guys over at SteveSpanglerScience.com have a great demonstration of how to make your light bulb (Steve Spangler is best known for his Mentos and Diet Coke geyser experiment that went viral in 2005). But while we’re going to follow most of their instructions, we’re also going to try out one or two other filament types.

A word of caution! Because making an incandescent light bulb requires that the filaments heat up, there is a potential for fire, getting burned, or inhaling smoke. ONLY PERFORM THIS EXPERIMENT WITH ADULT SUPERVISION!

The Materials

Lamp parts:

  • Toilet paper tube
  • Two test lead wires with alligator clips at both ends
  • 8 D-size batteries
  • Black electrical tape
  • A one pint glass jar
  • Aluminum pie plate

Filaments:

  • Fine steel wire
    • such as steel wool or picture hanging rope wire
  • Carbonized wood.
    • A piece of a throughly burnt stick will work or a piece of lump charcoal (used for cooking). Avoid using a charcoal briquette as these may be treated with petroleum products to make them ignite faster…and it’s almost impossible to get the alligator clips to attach to one
  • Soft mechanical pencil lead (graphite).
    • Graphite is actually a form of carbon. Pencil lead is actually a mixture of graphite and clay. The harder the pencil lead, the more clay in the mix. A regular #2 pencil lead will only smoke a bit so choose a much softer, darker pencil lead because it has more graphite in it and will be more prone to glow.

Directions

  1. To construct the lamp base, cut the toilet paper tube in half. Then, using black electrical tape, tape one end of your alligator leads so that they stick up above the paper tube. Attach your black wire lead to one side and the red wire lead to the opposite side.
  2. Make sure the other end of your alligator leads have extra length so you can touch them to the ends of the battery stick.
  3. Put the lamp base in the aluminum pan. This is to protect the table surface and catch any debris.
  4. Make the D-cell battery stick by taping the batteries together, end-to-end. I built mine by stacking the one battery on top of another, positive end to the negative end, and wrapping black tape just once around. Stacking ensured a good contact between each battery as I went.

Make it Shine

Select a filament and then hold above the lamp base and attach the alligator clips to it. Next, put the jar over the lamp base.

Touch the positive wire to the positive end of the battery stick and the black negative wire to the stick’s negative end.

The Result

It might take a moment or two. A few wisp of smoke might fill the jar.

Carbon lump filament.

Suddenly, the filament will begin to glow at its center.

Steel wool filament.

The glow will spread the entire length of the filament.

Graphite pencil lead filament

You’ll also notice that the jar will get very hot.

If your bulb’s filament begins burning you can cut the power immediately to put it out. Keep it covered until it cools.

The Science

The steel wool, carbon, and graphite all heat up because their molecular make up resists the flow of electrical current. Once they heat up beyond 977 ˚F, they begin to glow a dull red color. At 1000 °F, they appear more orange and 1300 °F, they glow white hot.

Because these filaments are not inside a sealed vacuum, how long they last depends on how fast they react the air. Steel wool burns up almost immediately. A carbon lump may last a few minutes to an hour depending on the size. A graphite pencil’s lead can last several hours.

Do you have any fun and kid-friendly science experiments you’d like to see us try for Fun with Less Kilowatts? Share with us in the comments!

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About 

A native of Wyomissing Hills, PA, Vernon Trollinger studied writing and film at the University of Iowa, later earning his MA in writing there as well. Following a decade of digging in CRM archaeology, he now writes about green energy technology, home energy efficiency, DIY projects, the natural gas industry, and the electrical grid.

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