Friday, April 24, 2015

Physics for Kids: Electricity

I've decided to do a small low stress Physics Club.   Once or twice a week (depending on how much prep time I have), we dip into Mom's Magic Box of Physics (NO PEEKING!).

Inside the box we find a variety of experiments grouped around a theme.  Really, I am shamelessly following my favorite experiments from Janice Van Cleave's Physics for Every Kid.

 So this week we started with electricity (I don't think we need to do laws of motion again!).

We actually started with watching the Bill Nye episode on electricity, so we got a good discussion of the basics. 

Electricity is a moving current of electrons.  What will it move through and why?

We started with a D battery and a variety of conductors and insulators.  You need to warn the kids, if it makes a circuit, the metal will get quite warm, quite quickly, so be prepared to drop it!

Did you notice that the shiny things tend to be conductors?  They shine for the same reason they conduct electricity: lots of loose electrons!

The conductors get warm because  they are imperfect: they are offering resistance to the electrons, so some of the electrons' motion is being converted by friction into heat.

If you have electric heat (or an electric stove or toaster!) that's how it works.

We also did quite a bit with static electricity because it's easy to see exactly what you are doing (rubbing electrons off of your hair) and because it's really hard to build enough of a charge to electrocute anyone!

 We hung two balloons from thread in a doorway.

At first, the uncharged balloons hang loose.

Rub one balloon on a kid's head and the balloons stick together (the negative charge will be attracted to the neutral because it's more positive - opposites attract).

Rub the other balloon on a kid's head and the balloons spring apart because they are both negatively charged (likes repel).

And this negative charge will attract/be attracted to all sorts of things!

Tissue paper, glitter, lint, little paper tents in plastic cups, water, the wall, your head...

It's fun to try different things!

The most fun experiment was one where I couldn't take a picture, but if you only do one experiment do this one: go into a dark room with a balloon and a florescent light bulb.  Rub the balloon on someone's hair and bring it close to the light bulb.

That's why florescent bulbs take so much less energy to run!

The grand finale was our home made electroscope:

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