What you Need
What to do
Turn off all the lights, close the curtains and wait a couple of minutes for your eyes to adjust to the darkness.
Take your sellotape, and then quickly pull some off the reel, whilst watching it.
What did you see?
What may happen
You will probably have seen some little flashes of light as the take was unreavelling.
Why does it happen?
When you pull tape off a reel you are separating two materials, the polyester tape and the adhesive. This is very like rubbing a balloon on your hair, a charge is transferred. This means that the adhesive ends up positively charged and the tape left on the reel is negative. This electric charge is why when you pull tape off a reel it is attracted to your fingers and seemingly anything else it shouldn't be.
As you pull the tape away you are pulling the positive charge away from the negative, you give the charge energy which is the same as putting it at a higher voltage. Some of the negative electrons will escape the tape and move through the air towards the positively charged adhesive. They transfer some energy to the air, which then releases it in the form of light which you can see.
UCLA researcher Carlos Camara decided to try this experiment in a vacuum, and found that it released x-rays powerful enough to take an x-ray image of a hand.