Make a Homemade Flashlight
Impress the kids with your new-found knowledge
You'll need a few basic supplies if you want to make a flashlight:
- One empty soda can with a curved bottom.
- An electrical power source: two D-size batteries.
- An electrical resistor (a device that requires batteries in order to operate): one 3-volt incandescent flashlight bulb. The bulb should equal the voltage of the combined batteries. Most D cells are 1.5 volts each
- Contacts to get the electricity from the battery to bulb; a 6-inch piece of flexible electrical wire will do (the soda can will act as a contact as well)
- Newspaper
- Masking or electrical tape
- Scissors
- A hammer and nail
- Sandpaper
Getting Started: Use the hammer and nail to make a hole in the bottom of the soda can. Enlarge the hole so the flashlight bulb will fit securely inside. The pointed end of the scissors should do this well enough. Carefully cut off the top part of the can. To avoid being injured on the exposed edge, use masking or electrical tape to cover it.
Cut the newspaper into 4- to 5-inch wide strips. Put both D batteries on the edge of the paper, lining them up in the same direction so that the top of one battery touches the bottom of the other. When the batteries are inserted into the soda can, the flat end of the bottom battery (or the negative end), will be touching the base of the flashlight bulb. Wrap the paper strips around the batteries forming a bundle. It should fit firmly inside the can.
Rub a small spot on the outside of the can with sandpaper to expose bare metal. Get rid of any building materials stuck to the ends of the electrical wire with the scissors. Tape one exposed end of the electrical wire to the bare metal spot on the can.
And you're done!
All you have to do is touch the unattached end of the electrical wire to the exposed positive battery end on the inside of the can. (You did leave the end exposed, right?) If it's not working and the kids are beginning to laugh and point, make sure the base of the battery is touching the flashlight bulb and you're touching the wire to the positive side of the battery. Remember, they should both be facing the same way.
If you really want to teach the kids a lesson in electricity, show them what happens when materials such as string, rubber or tinfoil are attached to the bare can and come into contact with the battery. Tell them all about the wonders of the simple circuit, containing electricity, conductors and a resistor; as crude as this one may be.
No soda can, no problem!
Almost anything with a spacious inside and holes in one or both ends can be used to create a flashlight. Since the can is used as one of the conductors in this soda can flashlight, make sure you have an extra few pieces of wire when using other casings such as a toilet paper roll. Remember, a contact needs to act as the go between, helping energy leave the negative end of the battery, travel through the light bulb base and back to the positive end of the battery.
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