Build a Light Bulb - Circuit Science
When you are conducting experiments and demonstrations using electricity, you'll use the science of circuits. Amazing things are possible with circuits including alarms, radios, and lights. In the Build a Light Bulb experiment, you'll use household items to construct a complete circuit that results in a homemade light bulb.
- Eight D-sized batteries
- Mason jar or other clear glass
- Electrical tape
- Pie pan
- Toilet paper tube
- Mechanical pencil refills
- Two sets of small alligator clips
- Using electrical tape, fix eight D-sized batteries together, end-to-end, with the positive ends connected to the negative ends. You've made a super battery!
- Use scissors to cut a toilet paper tube to a height that will fit comfortably (leave plenty of room) inside of a mason jar or other clear glass.
- Tape one positive and one negative alligator clip to one end of the toilet paper tube. Make sure the clip is facing up, away from the rest of the toilet paper tube.
- Tape the tube with the clips attached to a pie pan so that it stands upright, with the clips facing up.
- Carefully clip a mechanical pencil refill between the two alligator clips. The pencil refill needs to be in one piece, so be gentle.
- Place a mason jar or clear glass over the top of the toilet paper tube stand.
- Touch the other positive and negative ends of the alligator clips to the ends of your super battery.
- Give the circuit a moment to circulate the electricity and… voila! The pencil refill begins to glow.
How Does It Work?
When you touch the free ends of the alligator clips to your "super battery," you form a complete circuit. That means electricity flows freely through the entire apparatus that you have just built. This flow of electricity channels through the graphite-based mechanical pencil refill that is connected by alligator clips. The flowing electricity has a noticeable effect on the pencil refill. The thin refill begins to glow and give off smoke. This happens because the electricity heats the graphite refill to an incredible temperature. So, if you are hoping to save some money by using your own homemade light bulbs around the house,stick with the store bought ones. It's not as cool, but it is safer.
- Brand Matters Review by Sarah
We tried this experiment with different batteries and different brands of lead. We found that Duricell batteries worked the best and the Pentel HB lead worked the best.
(Posted on April 9, 2013)
- great Review by MILE
tHIS PROJECT IS LEGIT
(Posted on April 25, 2012)
- It worked! Review by Mrs. A
When I pushed tightly with the clips against the battery ends, the lead broke immediately. But when I barely made contact with the clips and the batteries it worked perfectly. The graphite glowed brightly for about 15 seconds. Very little smoke, but I used C batteries which might have made the difference. I tried it with 0.7 mm lead and it would not work. Great demonstration!
(Posted on March 22, 2012)
- spectacular results Review by al domz
Me and my group mates presented to our class as part of our simple process demonstration. Everyone was amazed by our presentation. Instead of the d size batteries we used the square battery of a spot light....it really worked and the pencil lead was actually really hot..one of my group mates touched it out of curiosity and got a small burn...i already warned him but he did not listen...anyways the presentation was successful.
(Posted on July 19, 2012)
- great Review by Eva
just like the bulb in the microwave experiment, this is great. We are so accustomed to ordinary bulbs, it is great fun to see the variations on the everyday reality.
(Posted on March 14, 2012)
- Perfect Timing! Review by Amy Lyttle
I have just started teaching electricity and this will be a fantastic demo to add to my lesson!
(Posted on March 14, 2012)
- It was amazing! Review by Gwen W.
We used a 6v latern battery and it worked great! It burned for a long time! It's so cool!
Julia, age 9
Alex, age 6
(Posted on March 4, 2013)
- Question Review by Student
I tried it and it did work, but have a question, how does the energy transfer through the lead? Or why does it transfer?
(Posted on March 26, 2012)
- Students were DEFINITELY engaged!!! Review by Lydia
My 6th-8th graders loved this experiment. After doing the 0.5mm lead their curiosity had them trying their own 0.7mm...and wondering if adding one more battery would help. I just attached insulated wire to some cheap alligator clips from RadioShack (I bought 2 types: the cheaper all metal ones actually worked better than the slightly nicer ones with insulated grips since the teeth were not as sharp, therefore breaking the lead less). The clips did get hot when doing it multiple times in a row, but this just shows that the energy is converted to multiple forms including light (EM) and heat (thermal). A previous review said Pentel lead didn't work, but it worked for my class.
(Posted on April 20, 2012)
- WOWIE Review by Cail
Wow, i did this experiment times, it worked 8 times and i was very impressed. the thiker the lead, the better it works!!
(Posted on May 21, 2012)