Saturday, November 15, 2008

Sparking in the Dark--It's Not What You Think...

Do you guys know Robert Krampf? He has a traveling show about electricity where he shows the effects of a Tesla Coil. He also has these nifty, handy dandy experiments that he sends out every week that you can do at home with easily available household items.

During a recent playdate, my kids went into the bathroom with their friend A. and started ripping off lengths of masking tape. I put a blanket down at the bottom of the door to make sure it was as dark as it could be. Then, I heard gleeful shouts as they were making all sorts of sparks in there. Positive charge met negative charge and then whamo! Spark!

Who says science is boring? Who says kids have to sit down to learn? Who says kids can't do things for themselves?

Here is Robert Krampf's experiment as it was e-mailed to me. See what sparks you and your kids can make.

There is a link where you can sign up and get these experiments too. Happy science!

Robert Krampf's Experiment of the Week
Electric Tape

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The Hottest Part of the Flame video


Electric Tape

Greetings from our home at the beach. I spent today on the beach at Washington Oaks State Park, taping for the "Rock" video. Who would ever have thought that I would be producing and starring in rock videos? Of course, with my beard and shades, I have been told I look a bit like a member of ZZ Top. I also got quite a bit of footage for upcoming videos on energy and the food chain, as well as having lots of fun playing in the rocks. The tide was low, and the tide pools had lots of fish, snails, clams, limpets, and other fun creatures to watch and videotape.

I really wanted to use the Electric Tape experiment for this week's video, but the sparks did not show up enough on tape. Instead, this week's members video is on scientific observations for the hottest part of the flame. In science, observation is very important, but it is also important to interpret those observations to reach the right conclusion. It may surprise you to find out that the hottest part of the flame is not at the top.

After the recent news articles about producing x-rays with adhesive tape, I thought it would be fun to do an experiment that would help explain how it works. You will need:

- adhesive tape

- a very dark room

You can use just about any kind of adhesive tape for this experiment. Some will work better than others, but you should get visible flashes from all of them. Before you turn out the lights, pull a little of the tape away from the roll. It is much easier to do this when you can see what you are doing. You may want to fold the end of the tape over, to make a tab to hold onto.

Turn out the lights and get the room as dark as possible. Wait a minute or so, to let your eyes adjust to the darkness, and then look for sources of light that you can block. You may be surprised that so much light is coming into your "dark room." If you can't get the room dark enough, you may need to use a closet instead. The darker the room is, the easier it will be to see the results.

Once your eyes have adjusted and the room is very dark, you are ready to make some sparks. Hold the roll of tape in one hand. With the other hand, grasp the tab on the end of the tape. Watching the roll, quickly pull some tape from the roll. As you do this, you should see flashes of light coming from the tape as it pulls away from the roll.

Cool! Try it again. It is always a good idea to repeat experiments, especially the fun ones. Also, you don't have to worry about x-rays. That only happens in a vacuum.

What is happening? When you pull the tape from the roll (or from another surface), the rapidly stretched adhesive develops a strong positive charge at one end, and a strong negative charge at the other. This property, called triboluminescence, is also what causes the sparks that you see when you bite a wintergreen candy in a dark room. Electrons jump from the negative area to the positive area, producing a spark makes the flash.

In air, all you get is the spark, because the air slows the electrons, but in a vacuum, the electrons hit with enough speed to produce x-rays. Of course, now I want to know if biting a wintergreen candy in a vacuum also produces x-rays. I can see it now. X-ray machines powered by wintergreen candy. Boy, that would be a Lifesaver!

Have a wonder-filled week.


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