Vacation Exploration: The Science of Luminaria

light-celebrations-luminariaLuminaria are a beautiful addition to these longer winter nights, and you may especially encounter these glowing paper lanterns along driveways, sidewalks, or even on houses on Christmas and New Years Eve. While they are traditionally made using paper bags with small candles inside, why not turn luminaria into a science activity? Because, you know, science. Below is a description for how you can investigate basic circuitry with your children, and create something beautiful as a result. And it’s a way for you to find utility in all of those no-longer-working holiday lights that you just can’t bring yourself to throw away. Life is good.

 

Suggested Materials

  • D or C-cell batteries (2 per luminaria)
  • 1 string of holiday lights (even one that is not working any more). From this string of lights, you will prepare:
    • Stripped individual light bulbs (see instructions below)
    • Stripped wire pieces, 6 inches long (see below)
  • Scissors and wire strippers (optional)
  • Masking tape or electrician’s tape
  • Small paper lunch bags (white or brown)

Preparation

If this is your first time playing with batteries and bulbs, you can try the “Lighting a Light Bulb” activity from Boston Children’s Museum’s “Beyond the Chalkboard” afterschool curriculum. It serves as a good foundation for this activity. Just replace the word “students” with “kids” in the instructions. Or with the word “me”, if you’re awesome enough to be playing around too.

There is some preparation for this activity, but you and your kids can do it together. It looks like a lot, but it is quite simple – the instructions below are just very detailed. And once you have it done, you’ll have bulbs and wire to use for years to come!

1) First job: prepare the bulbs and wire. Cut right through all the wires at one end of the string of lights with the scissors. Unless you have a very old string of lights, you’ll find that after the first bulb, you have 3 wires intertwined. Two of these wires will be free and the third will connect all of the bulbs together. Unwind the 2 free wires—you’ll be cutting them into pieces and stripping them later. Now you should cut the wire connecting the bulbs. Cut the wire halfway between each bulb—this will leave bulbs with wires of equal length:

cutting-bulbs

2) Once you have the bulbs separated, you’ll need to expose the metal part of the 2 wires on each bulb using the wire stripper (if you are careful, you can also strip wire with scissors). Most wire strippers have holes near the handle—open up the stripper and place 1 of the bulb’s wires about 1 inch into the hole of the wire stripper that’s just a little bit smaller than the wire. The 14 or 16 gauge hole works for most holiday lights. Squeeze the handles of the wire stripper together and pull away from the bulb—with practice, you’ll pull away just the plastic coating of the wire, leaving the metal part inside exposed. Your wire is now as naked as the day it was born:

wire-stripper-and-bulb

3) Once you’ve stripped a few bulbs, cut some pieces of that extra wire you put aside—anywhere from 6 to 12 inches a piece should be good. Strip both ends of these wires. Now you’re ready to play!

Get Into Some Science

Experiment with 2 batteries, a few bulbs, and some wire alongside your child. Share ideas and questions together. Can you light up one bulb with one battery? How about one bulb with two batteries? Or two bulbs with two batteries? Lots of combinations to play around with!

IMPORTANT NOTE: If you are using a string of lights that wasn’t working, you likely have some dead bulbs. Nothing is more frustrating than trying to do science with faulty equipment. Test the batteries and bulbs to make sure that they are all working. You can do this by lighting each bulb up with a battery that you know works, and then testing a working bulb with each of the other batteries.

So…..how the heck do you light these bulbs? I’m glad you asked. Here is a description…which is NOT AS FUN AS FIGURING IT OUT, but also not frowned upon if you’re having a hard time lighting those suckers up.

If you touch one of the bulb’s wires to one end of the battery, and the other wire to the other end of the battery, the bulb should light up. Yay! When you do this, you’re creating a circuit—an unbroken circle that allows the electricity to travel through the battery, along one wire, into the bulb, back down the other wire and back into the battery. As soon as you break that circle, the electricity is no longer flowing, and the bulb won’t light.

Now try to make a circuit using a battery, a bulb and a piece of wire (make sure the ends of the wire are stripped!). Remember that the electrons in the battery want to travel in a circle. If you twist one end of the wire together with a wire from the bulb and touch the 2 free wire ends to each end of the battery, the bulb should light up again.

Next, keeping the 2 wires touching the battery, untwist the bulb wire from the end of the wire piece. The light goes out—touch them together and it lights up again. You’ve just made a switch! This is how a switch works—it’s simply a break in the circuit that can be reconnected. When you do this with your kids, make sure they try it themselves—don’t show off your expertise right away. Let them attempt lots of different ways of lighting the bulb until they get it right. They may get frustrated, but it’s activities like this that can teach kids perseverance.

Taking It Further

OK, so what about those luminaria things you talked about. Good question. This is where the science gets pretty cool. Here is your challenge: Can you light 3 bulbs at the same time with just on battery? Try it.

After a few minutes of tinkering around, you may have arrived at at least one solution. If so, how bright are the three bulbs? If they are dim, is there a different way of wiring them so that they are all bright? That sounds like a leading question…

There are two common ways of lighting multiple bulbs. The first is stringing them together in a line, like this:

bulbs-series

This is known as wiring in “series”, and looks a lot like the string of holiday lights. The problem is, the more lights that you add to the string, the dimmer the lights will get. This is because the bulbs are all sharing the battery power. Here is a second way of twisting the bulbs together:

bulbs-parallel

These bulbs are not in a line. A wire from each bulb is twisted together with the others. The second wire from each of the bulbs are all twisted together. This is known as wiring in parallel. When these two 3-wire connections are touched to the 2 ends of a battery, all 3 bulbs will light up just as bright as when 1 bulb is lit up with the battery. This is because each bulb creates its own path, drawing energy from the battery.Cool, right?

Now try lighting your three bulbs in parallel with 2 batteries. You will discover that the batteries need to be touching end-to-end, facing in the same direction:

batteries-together

By touching the wires to the 2 ends of this setup, you will be able to light your bulbs more brightly than with a single battery. You can use tape to keep the wires attached to the batteries.

Making the Luminaria

OK ENOUGH ALREADY – WHAT ABOUT THE LUMINARIA? Thanks for your patience. Tape two batteries so that they stay together, and tape your wired bulbs to the batteries so that the lights remain on. Open up a paper bag, place it on a table or on the ground, and put the batteries and lit bulbs in the bottom of the bag. Now turn off the lights. Whoa – pretty. Make a few of these bags (you can make some with small votive candles in them. Some soil or sand at the bottom of the bag can help secure the candles and also give the bags a little weight so they don’t blow over). Make a path with these bags inside or outside, and enjoy the show…and feel satisfied in the fact that science helped you get there.

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