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Electric Tape

I really wanted to use the Electric Tape experiment for a video, but the sparks did not show up enough on tape. Until I can afford one of the new, super low light video cameras, we will have to get by with reading the text version. 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.

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 tiny spark that 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. Researches are working on this as a way to take X-rays in the field, under conditions there is just not way to bring in an x-ray machine.

Of course, now I want to know if crushing 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.