Science | Science Experiment of the Week 10 | 308 - Static Glow

Electricity, Plasma, Flourescent Bulb, Mercury, Vapor - How can a balloon produce enough electricity to light a fluorescent bulb?

This Week's Experiment - #308 Static Glow

These experiments are from Robert Krampf - The Happy Scientist

The cold weather has made the static electricity much better (or worse, depending on how you look at it). While the humidity of living at the beach usually makes our lives fairly static free, our dog and cat are discovering that in this weather, almost any touch can involve a spark. With all of that static, I thought that I should use it for this week's experiment. To have some fun with static, you will need:

a fluorescent bulb
a balloon
a dark room

First, be very careful with the fluorescent bulb. They break easily and contain mercury, so if young children (or clumsy adults) will be using them, go to the hardware store and get one of the cheap, plastic covers that fit over the bulb. That will make it safe and easy to clean up if the bulb breaks.

Blow up the balloon and tie it off. Rub it on your hair and see if it will stick to the side of your head. If it sticks, then you are getting plenty of static. If it does not, then you probably have too much humidity (or too little hair, like me). Dry the balloon and your hair with a hair drier and try it again. You can also try someone else's hair.

Once you are getting plenty of static, go into the dark room. Hold the balloon in one hand and the fluorescent bulb in the other. Have someone turn out the lights and then stand there until your eyes get used to the dark. Be sure that the room is very dark, even when your eyes adjust. Even a little light coming under a door can make it difficult to see the results.

Now comes a challenge to your coordination. In the total darkness, you are going to rub the balloon on your hair. Then touch the balloon to the side of the fluorescent bulb. If the room is very dark, and if you are getting plenty of static and if your eyes are adjusted to the darkness, and if you can find the fluorescent bulb in the dark, you should be rewarded with a nice flash of light. It will not be a bright flash, but it should be enough to see.

How can the balloon produce enough electricity to light the fluorescent bulb? To answer that, we need to know a little about how light bulbs works. A regular, incandescent bulb lights by using the electricity to heat a wire filament inside the bulb. When this filament is hot enough, it begins to glow and you get light. Incandescent bulbs need a lot of amperage. Amperage tells us how much electricity. They do not need much voltage, which is how hard we are "pushing" the electricity through the wires. The electricity you are generating with the balloon is just the opposite. It has a very small amperage and very high voltage. You would not be able to light an incandescent bulb with it.

A fluorescent bulb does not produce its light with a wire. Instead it uses a gas. Most of the air has been removed from the tube. It has been replaced by a tiny amount of mercury vapor, at low pressure. When high voltage electricity forces it way through the gas in the tube, the gas is changed into plasma (the fourth state of matter). Plasma is like a gas, but some of the electrons have been ripped from the atoms. The plasma is a good conductor of electricity. It also gives off light. Unfortunately, the light this plasma gives off is ultraviolet, sometimes called black light. It is a color that our eyes cannot see. Luckily, the white powder on the inside of the glass tube glows under ultraviolet light, and we can see the light from that glowing powder. Forming the plasma in the fluorescent bulb requires high voltage, but does not need much amperage. That is exactly what we are producing with the balloon, so it can light the bulb.

You don't need to have the balloon to light the bulb. Anything that produces a good static charge will do it. Try taking a load of clothes, fresh from the drier, into the room. Touch the bulb with the socks as you pull them from the other clothes. In the dark room, you will notice tiny sparks as you pull the socks away from the other clothes. You see those sparks because the electricity is changing the air around you into plasma. The air you breathe is mostly nitrogen, which glows purple when the spark changes it to plasma. When you touch the socks to the bulb, you should see a faint, white flash as the mercury vapor is also changed to plasma.

Feel free to try other sources of static, but stick with static. Do not try to use the electricity from a wall socket. It would not work, because it is too low voltage. The fluorescent lamp steps up the voltage so that it can light the bulb. It would also be very dangerous because household current can kill. Be safe and have fun. And fold the laundry when you are done. Have a good week.

If you have comments, questions, or would like to report a broken link, please send an email to Cheryl at byclc@live.com

© 2000-2024 Nicholas Academy
site map | privacy policy | by CLC | Micro-Ways