Science Saturday #3

Okay, so technically it’s Tuesday, but I promise you: this is a science post worth waiting for!  

This week’s experiment: Make Your Own Ghost 
(aka: how to make a light bulb glow without plugging it in)

The purpose of this experiment is to illustrate how we can generate electricity with our own bodies that can be used to make a fluorescent light tube glow.

Stuff you need:                                          

Latex balloons

Long fluorescent light tubes

A dark room (we used a storage closet and a bathroom with no windows)

Curious Kiddos (costumes optional) pictured l-r, Kiddo JPO, Kiddo LPO, Kindergarten Kiddo)

We began this experiment by asking our Kiddos to predict how we could make the light tube glow without plugging it in to a socket.  Our Kiddos guessed, “You can make it glow with the sun.”  And then… “You can use static electricity!”  Bingo.

This experience will be a lot more interesting for your Kiddo if you spend some time building up his or her background knowledge a bit.  Keeping in mind that this is an experiment for Kindergarteners (and one 3 year old sibling), we kept our overview pretty basic.

First, talk with your Kiddo about how light is a form of energy.  This is a concept that even very young children can grasp onto.  Next, explain that the fluorescent tube is coated inside with a special chemical (phosphorous powder) that is turned on (glows) when it comes in contact with energy.  Describe how you are going to use the balloon to create the kind of energy that the light tube needs to glow.  Finally, explain that in order to see the light tube glow, you must conduct your experiment in a very dark space.

Step One: Inflate and tie the balloon.

Step two:  Find a Dark room where you can shut out most incoming light.  We used a closet, but a dark, windowless interior room would work too.  You can try to do this under a very heavy blanket if your Kiddo gets too scared of, say, being stuck in a small dark room; just be sure that all ambient light is shut out.

Step Three: Place one end of the tube on the floor and hold it upright.  We found it easier for the grown-ups to handle this part of the experiment.  We also found that if you are working on non-carpeted surfaces, it works best if the grown-up holding the tube is also wearing socks and can rest one end of the tube on the top of her toes.

Step Four: Rub the balloon up and down the side of the tube as fast as you can.  Within seconds the tube will start glowing.

Here are two pictures that we managed to get of the glow.

Don’t they look like ghosts? 

Extra Credit: If your Kiddo is older (or a genius) you can spend some time explaining about the ultraviolet light that melts the drop of mercury inside the tube which turns into a vapor laden with electrons that then interacts with the phosphorous powder coating the inside of the tube.  This is explained in detail in Janis VanCleave’s book Physics for Every Kid, the book we used for this experiment.

VanCleave’s book says, “Once the tube starts glowing, even the nearness of the balloon causes light to be produced.”  We weren’t able to reproduce this result, but honestly – who cares?  This experiment’s results were neat enough on their own.

Cost for this experiment: the two pack of light tubes was $5.99 and the balloons were $2. 
A big THANKS to Momma K and Kiddos J&L for experimenting with us today!

P.S. Getting the photo of the glow was a bit tricky.  If you want to know how we did it, leave a comment and I’ll reply – otherwise, the post gets too long.