This is a super fun kids science experiment for demonstrating static that even the Littlest Sparks can enjoy and take part in safely.
We ended up leaving our apparatus out all week because our Little Sparks were so fascinated by this exploration of static electricity that they kept returning to it again and again to try out different variations on the experiment. They were keen to show off their new found knowledge about positive and negative charges to all our visitors!
If you would like to try making our Static Popcorn science experiment you will need to gather together the following items:
A sheet of clear perspex. We got ours by dismantling one of those clear plastic clip frames that people use for displaying certificates. Hard ware stores will sell sheets of perspex, although you only really need a piece that is approximately 30cm x 20cm.
Four supports for each corner of the perspex that are about five centimetres high. We used wooden toy blocks, you could use small food tins from the pantry.
A piece of paper at least the size of your perspex sheet. We used bright pink so we could see our ‘popcorn’ clearly, but plain paper is perfectly good.
A piece of woollen cloth – a woolly mitten is perfect!
For the ‘popcorn’ we used little pieces of broken up styrofoam packaging, you could use rice, cereals such as Rice Krispies or even plain popcorn! Why not experiment and see what happens?
What to do:
Place your paper on the table and scatter your ‘popcorn’ over it. Using your four supports, balance the sheet of perspex over your paper and popcorn.
Next rub the woollen cloth vigorously backwards and forwards across the top of the perspex sheet for a good 60 seconds.
Now stand back and observe. Resist the temptation to interfere with the apparatus, just watch for four or five minutes (very difficult for some Little Sparks!) Carefully note what happens. Can you think of explanations for this?
Repeat the experiment using a different variable each time – you might alter the type of cloth you use, or alter your popcorn material or you might try rubbing harder or longer to increase the static charge. Observe, make notes, think of possible explanations.
What happened here?
Before you began the experiment your ‘popcorn’ and the plastic sheet were electrically neutral. In other words they both carried equal numbers of positive charges and negative charges. Some materials such as wool (you might also try some fur) give away their negative charges (these are called electrons) very easily through friction. Other materials, those that we tend to think of as good insulators (materials that do not conduct electricity) such as rubber and plastic are very good at collecting extra negative charges. When you rubbed your wool against the plastic the friction caused the wool to pass on extra negative charges to the sheet of perspex.
The charged perspex had an interesting effect upon your popcorn causing it to become polarized. The positive charges in your popcorn moved to the upper side while the negative charges were pushed to the underside of the popcorn. Negative charges and positive charges are attracted to each other. The positive charges in your popcorn were attracted to the negative charge of the plastic sheet causing them to jump up and stick to the plastic. However, after a while extra negative charges are passed to the popcorn and when both surfaces become negative they are repelled and the popcorn is pushed down again.
Static electricity builds up on all sorts of surfaces. Your TV screen or computer monitor becomes charged and they attract the dust in the room causing it to stick to their surfaces just like your popcorn did to the charged perspex. Sometimes when you comb your hair with a plastic comb the plastic surface will collect negative charges leaving your hair positively charged. Strands of hair are repelled from each other causing that ‘fly-away’ effect because they have all become positively charged. What other examples of static build up can you discover?
Something Else To Try:
Blow up a balloon and rub it against your sweater or hair. The friction causes your jumper/hair to give up some of their electrons leaving the balloon negatively charged. Now turn on the tap at the kitchen sink so that there is a thin, steady stream of water and hold the negatively charged balloon close to the stream of running water. You will notice the stream of water bending towards the balloon. This is caused by the positive charges in the water being attracted to the negative charge of the balloon.
Visit our article on Snap Circuits For Kids to have fun learning more about electricity.