Make a Light Bulb

A light bulb is made when metal filament is heated to the point at which the wire glows. The most well-known type of light bulb is the incandescent light bulb, which is the version used in most homes. Use these steps for making a homemade light bulb.

Steps

Making a Simple Graphite Light Bulb

  1. Head to your local art store and pick up some pencil lead. You should use the kind you get in mechanical pencils -- the thin, solo pieces of graphite that you can usually buy in packs. The thinner, the better -- try something like .5mm thickness.
    • Pencil lead actually isn't lead at all, it is graphite. Graphite is an electrical conductor, making it a good filament for homemade light bulbs.
  2. Round up the supplies needed for you bulb. Everything here is easy to round up at a local hardware store, if you don't already have it all at home. You'll need.
    • Two strands of copper wire (roughly 1-2 feet, each)
    • Four electrical clips
    • One clear glass jar
    • Five or more batteries
  3. Hook the copper wires up to the electrical clips. The ends of each wire should have a clip on it. If you don't have clips, you can still make a light-bulb. To do so, curl each end of the wire into a little round hook.
  4. Attach your batteries together in series. This simply means you tape them together, end to end, so that they all work together to provide power. Make sure you line them up positive end to negative end. Then use electrical tape to secure all the batteries together into a long rod.
    • You must arrange the batteries so that there is a positive node on one end, and negative on the other.
  5. Clamp a copper wire to one end of the batteries. Usually, you'll have a wire with red clips and one with black. Hook one end of the red clips up to the positive end of the batteries, but leave the other clip off for now. If you hook everything up, you'll actually be turning the light bulb on before you're ready. You could get burned if you're not careful
    • You can reverse the red and black if you want-- you just need different wires on each end.
    • Remember you only want to hook up one wire right now.
  6. Stand up the two remaining clips, then clamp the graphite between them. Think of making an H-shape, where the two clips are the sides and the graphite is the horizontal line in the middle.
    • The longer the graphite, the longer your bulb will last.
    • Use some tape, glue, or modeling clay to help stick the clips face up.
  7. Put the glass jar on top of the clips and graphite. This isn't strictly necessary, as the graphite would still light even without the jar. But the process creates smoke, and the graphite can shatter. Moreover, having an actual "bulb" helps create a more even light.
  8. Attach the final wire to the other end of the batteries to turn the light on. You are making a simple circuit, connecting the batteries in an electrical loop. The light comes from the graphite -- as electricity flows through it, it heats up and emits energy in the form of light and heat. Thus, your light bulb!
  9. Troubleshoot to get a stronger light. If the light is weak, or isn't working, there are some things you can do to make sure you get a working light.
    • Check the graphite thickness. While larger thicknesses work, 0.5 mm seems to work best.
    • Add a few more batteries. Also, make sure that the ones you have are touching end to end.
    • Make sure the wires are snug and well-connected to the batteries.

Using Iron Filaments

  1. Cut some copper wire into two sections, roughly 1-2 feet each. Copper is a great conductor of electricity, and most wiring is copper. You need two strands about 1.5 feet (0.4572 m) long.
    • Use small wire cable cutters to cut the copper wire.
  2. Remove 1" of shielding from each end of the wire. The shielding is the rubber that covers the copper wire. Removing it can be achieved by carefully squeezing the cable cutter so that it cuts through the shielding but not the wire. The shielding can them be stripped from the ends with your hands.
  3. Use the nail to pierce two holes into a cork. The holes should be in the middle of the cork about 1/2" apart. This cork will hold your wires in place. Think of it as the bottom, metal part of your light bulb.
  4. Thread one end of each copper wire through the cork. Leave about 2" or so exposed above the top of the cork.
  5. Bend the end of the two strands inside the cork into a hook shape. The hook of each strand should curve the same way. This will hold onto your filament, the part of the bulb that actually lights up.
  6. Cut the iron wire into 1-1/2 to 2 inch (3.8cm to 5cm) strips. Make five strips. The thinner your wire is before beginning, the better. Thinner wire will almost always result in a better light.
  7. Twist the five iron wire lengths together with your fingers. You want a long braid of wire. It needs to be tightly wound as well.
  8. Place the twisted iron wires onto the copper hooks, making sure it touches both copper strands. For an even better fit, you can tighten the hooks around your iron filament. The more of it touching, the better.
  9. Lay the jar on top of the cork. This is your "bulb." It will help protect from shock, but also creates a more concentrated light.
  10. Wrap both ends of the wire around separate ends of a battery to turn the light on. If you have electrical clamps, they will be much safer and easier to use. If you don't, make sure you're wearing rubber-soled shoes and have safety gloves on. Attach one wire to each end of the battery to complete the circuit and "turn on" the light bulb.
    • You can use any battery, but starting small is usually best. C or D batteries (1.5 V each) will do the trick.
    • If you're not getting enough light, try attaching your batteries in series.
  11. Troubleshoot if you're not getting enough light. This is a simple scientific machine, so their are simple ways to test and fix bulbs that don't work.
    • Ensure all the ends are touching. You must have a complete, unbroken circuit to get light.
    • Thin out the filament. Try it with only 3-4 strands. You could also replace the iron with graphite, as mentioned in method one.
    • Add more power. Use a bigger battery, or attach multiple batteries together, for more power and more light.



Tips

  • If the light bulb doesn't light up after you've connected the copper ends to the battery, check your connections.
  • Using more than five iron strands to make your filament will increase the brightness of your homemade light bulb.

Warnings

  • Using a battery weaker than 6 volts will not light the bulb well. Using a battery stronger than 6 volts could be dangerous because of weak construction.
  • Do not touch the filament after it has been lit. It will be very hot for at least ten minutes following its use.
  • The filament (the twisted iron wire) might move when putting the cork stopper into the glass jar. Make sure the components are in place before stopping the jar completely.

Things You'll Need

  • Glass jar
  • Fitted cork stopper
  • 1 inch (2.54 cm) nail
  • 3 feet (0.9144 m) shielded copper wire
  • Iron wire
  • 6-volt battery
  • Wire cutter

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Sources and Citations

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