Build a Light Bulb - Circuit Science

Create a battery-powered light bulb from household items

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.

Materials

Eight D-sized batteries
Mason jar or other clear glass
Electrical tape
Pie pan
Scissors
Toilet paper tube
Mechanical pencil refills
Two sets of small alligator clips

Electricity isn't something to take lightly. Make sure you have adult supervision when experimenting with electricity.

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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.

Amazing Experiment!!!

Sam - May 3, 2013

This user gave 5/5 stars

My 10 year old niece loved it! I do have some suggestions -
1. Make sure your batteries are tightly connected. We did a test with a small fan to make sure the batteries were connecting. We even used two rules to make a splint to ensure the batteries remained in a tight formation.
2. We found it worked best with .9mm pencil refills. .7mm and .5mm also had good results but .3mm broke immediately on contact.
We used Pental brand refills available at Staples.
I would guess that those having trouble are not connecting the batteries together tightly.

Brand Matters

Sarah - April 9, 2013

This user gave 5/5 stars

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.

It was amazing!

Gwen W. - March 4, 2013

This user gave 4/5 stars

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

Lots of Trial and Error

Richard Moore - December 11, 2012

This user gave 4/5 stars

I noticed the first reviewer had trouble getting this to work. I did as well. I went back and forth to the office supply store to buy various brands and widths of lead. Still didn't work! After 3 hours I simply gave up.
The next morning before school I taped together 10 D batteries, made sure my wires were conducting, used Papermate .5mm lead, used new tight alligator clips, and a much smaller jar. Worked perfectly! I used .7mm as well. Then I used a very thick lead shaved from an HB pencil. It took 18 volts, but worked. Couple this with Time Magazine's Man of the Year article on Thomas Edison and you've got a pretty good lesson in reading, critical thinking, and of course, science.

didn't work despite troubleshooting

Cristy - November 5, 2012

This user gave 1/5 stars

I could not get this to work. I did not have D batteries around, but I tried it with 8 or 9 C batteries, 1 or 2 big square lantern batteries, 8 and 16 AA batteries... basically lots and lots of battery combinations. I would see smoke, but now glowing. I tried a little motor between the clips to make sure my circuit was good, and it was fine. Tried with a jar and without a jar, even tried replacing the O2 in the jar with CO2 via vinegar/baking soda gas "poured" in to it. Put some Nichrome wire between the clips and got a little glow, but just orange wire. Nothing impressive. I would test this in advance to not end up with disappointed kids. I am a pretty disappointed 40-something!

spectacular results

al domz - July 19, 2012

This user gave 4/5 stars

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.

WOWIE

Cail - May 21, 2012

This user gave 4/5 stars

Wow, i did this experiment times, it worked 8 times and i was very impressed. the thiker the lead, the better it works!!

Lightbulb Experiment

Dawn Hardy - May 17, 2012

This user gave 4/5 stars

My second graders used .7mm leads and the experiment worked beautifully! We actually did the experiment a few times using different battery combinations with interesting results. There really is a difference in brands. This was great!

great

MILE - April 25, 2012

This user gave 5/5 stars

tHIS PROJECT IS LEGIT

Students were DEFINITELY engaged!!!

Lydia - April 20, 2012

This user gave 4/5 stars

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.

Another winner!

Marlene Thomas - April 4, 2012

This user gave 5/5 stars

Last week we made the battery so this week we made the bulb. This is a fantastic activity. It takes some time to get it to work which I like since it gernerates questions from the kids. Once it worked, I couldn't get the kids to stop talking about it. Amazing results!

Question

Student - March 26, 2012

This user gave 4/5 stars

I tried it and it did work, but have a question, how does the energy transfer through the lead? Or why does it transfer?

It worked!

Mrs. A - March 22, 2012

This user gave 4/5 stars

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!

Type of pencil lead is important

Ruth TenBroek - March 21, 2012

This user gave 5/5 stars

I'm preparing for a science class on electricity, so my boys and I tried building the light bulb. The graphite kept breaking without glowing at all(we used Pentel brand Super Hi-Polymer Lead). I went back to the store and bought a different brand(Papermate), and it worked perfectly!!

impressive, but hard to get to work

Science lover - March 16, 2012

This user gave 4/5 stars

10 of the 12 pencil leads we used broke immediately with a puff of smoke. Only two worked (for about 10 seconds). It was impressive, but it would be a good idea to buy extra pencil leads. I will also try thicker ones next time also, to see if that makes any difference

Nice Activity, Chance to Experiment

Bill Polacheck - March 15, 2012

This user gave 5/5 stars

I used this activity early on in my electricity unit in sixth grade. I did it under an exhaust hood out of fear of tripping smoke alarms, but I don't think much smoke would have escaped. I initially tried using two six-volt lantern batteries tied together but it didn't work. Any idea why?

Light bulb review

Ami - March 14, 2012

This user gave 5/5 stars

Awesome! Is the smoke from the graphite burning as it is conducted through the resisting filament until the oxygen is used up? Then it glows! It sure takes a lot of energy for this light bulb!

Perfect Timing!

Amy Lyttle - March 14, 2012

This user gave 5/5 stars

I have just started teaching electricity and this will be a fantastic demo to add to my lesson!

great

Eva - March 14, 2012

This user gave 5/5 stars

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.

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