Thursday, July 08, 2010

"So We Beat On... against the current, borne back ceaselessly into the past" -The Great Gatsby, F. Scott Fitzgerald.

Although I don't approve of many of Mr. Fitzgerald's life choices (the same goes for his wife's. Read A Moveable Feast by Hemingway and you'll see why), he is a brilliant writer and I've often taken stuff from him.

So, 5 days left in this program. A little over a week. And then I'm free. But let's not get ahead of ourselves. Let us recap.

Tuesday we covered Electicity/Circuits.

Tuesday we did basics of circuit building namely: how do you make a light bulb light up with a bulb, a battery, and a single wire? I realize I'm pushing these kids beyond some of their limits, as I remember doing this experiment in 6th grade myself, though there's no point in teaching if I don't push their limits and expand their comfort circles.

An interesting thing about my day: As the day progresses, the children get progressively younger. I start with the oldest kids right after lunch, and end with the youngest ones. This is slightly problematic in that since I'm teaching the same material for each class, I have to scale the lesson appropriately. Starting with the oldest ones is easy, as I can generally explain the content as I understand it on a basic level. But I have a hard time gauging how much I have to simplify for the younger kids. For the older kids, I made an analogy that a circuit is like going to the market, where the market is the battery and the bulb is your home, and you need a car (electron) to carry the charge (food) along the road (wire) back to your home. To explain why you need to connect a second wire to the negative terminal, I told them it's like a one way street, and you can't just go back along the same wire. I thought this analogy would work well with the little ones, but I failed to take into account a few things. First, some little kids don't know what a battery is. The concept of a one-way street was also lost on them.

But the lesson went well overall. A lot of the kids burned themselves because they don't listen to directions. I spent a good 10 minutes going over what a short circuit was and why you should never make one. I explained that it would burn them. Yet, not 2 minutes after I finish explaining what not to do, I hear a "ouch". Which prompts the other kids to short their circuits just to see what it feels like. At the end, everyone was able to light their bulb, which is all I was looking for.

So I have Zachary Litman to thank for showing me the coolest thing I've seen in a long time. It's called a homopolar motor, and after taking much much physics over the years, I know why it works. But who cares, here's the one I made:

This is one of the few things that truly impressed me. Part of it is its simplicity, and part of it is how well it works. A neodymium magnet (I bought mine at Wal-mart. It was in the crafts section), a AA battery, and a loop of copper wire. I showed this to the kids and it blew their minds. I think one of the coolest details I noticed is that the wire must be copper wire. Why you might ask? Well, copper is diamagnetic (one of the many things I learned from the 2nd semester of PChem Lab. That, and how awesome lasers are), meaning there won't be any drag from its interaction with the magnets. I originally tried it with a paperclip loop, and it did not work at all. These little details fascinate me.

One thing that never fails to amuse me is that the little kids aren't always the ones that are most impressed by the experiments. A lot of the times, its the junior leaders who are the most thrilled to come to my class. All the junior leaders are High School students, but they act like little kids when they see some of the experiments. The homopolar motor was a big hit with a bunch of them. I also know one of the leaders, Jody, was fascinated by my inherited traits lesson. Who said only the little kids were there to learn?

Here's my shirt pocket from that day:

Be not fooled by this simple, unassuming shirt pocket. Like an iceberg, 8/9ths of the stuff is hidden below. In this shirt pocket, should you care to dig, you would have found: 7 AA batteries, 5 2,4V 0.2A light bulbs, a loop of copper wire, a pair of wire stripping pliers, and 8 neodymium button magnets, and a Nature Valley Oat and Honey Granola bar.

A note about the above shirt. This shirt is rather busy. But I don't really have a problem about it, since I don't usually care what I look like (since I can't really see myself unless I look in a mirror). But what is terribly embarrassing is going into Long's Drug Store and discovering that you are wearing the same shirt as the employees. What makes it worse is being asked where the Polydent is by little old ladies.

And the countdown begins.


  1. You always amaze me with how much you can fit in a shirt pocket. I guess looks can be deceiving. A shirt pocket has more volume than it seems.

    Please explain the physics to me behind a homopolar motor.

  2. Haha, I was just pondering - have any of your students' parents found your babybunsenburners blog and told you about it? Do your own parents know about it and read it?

  3. So there's a current running through the wire, that runs perpendicular to the magnetic field produced by the magnet. By F = IBl and the Right Hand Rule, this produces a force/torque on the wire, causing it to spin. This is actually how all electric motors work (though many don't use fixed magnets). It's homopolar, because unlike most motors which run off of AC, the polarity of the magnet/direction of current doesn't change in time.

    My parents kind of get the oral version of my blog. However, they don't really know about it. Not that I'm hiding, it's just that my parents are rather tech challenged in many regards, and telling them about something like this would cause more problems than is worth it.

  4. Oh... right, now I remember that good ol' physics.

    Haha, but apparently your parents are tech savvy enough to Google your name and stumble upon my website hahaha.