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David Anthony Colarusso - Sadly not Havoc Dinosaur
Intermittent musings on the law, science, education, technology, design, and life. Also, I build things: furniture, software, reasoned arguments... To learn more about that, click a persona below for my eponymous website.

Electricity & Magnetism

How to build a simple electric motor, plus how it works.

by David Colarusso - March 3rd, 2007

A fast-paced time-laps demo of how to build your own electric motor, this segment was a lot of fun to make. I hope you enjoy it. Plus, you can now subscribe to the Tabletop Explainer via iTunes.

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Also, by popular demand, here’s a TROUBLESHOOTING GUIDE

First, it’s important to understand the context of the “Build Your Own Motor…” video. It’s a demonstration aimed at solidifying the ideas presented in two earlier videos. If you haven’t already, you should watch the whole set:

1) What is the magnetic field?

2) Electricity & Magnetism Hand Rules (part one)

3) How to build a simple electric motor, plus how it works. (above)

The main idea here is that charges moving through a magnetic field experience a “push” perpendicular to the direction of their motion. This force is also dependent upon the direction of the magnetic field. The fact that the wire is stripped on only one side alternates the current from “on” to “off” every half rotation. So halfway through the spin, the ring coasts through until it gets current again receiving a “kick.” It’s a poor man’s commutator. The particulars of this kick/force are discussed in the second video. Armed with the knowledge from the above videos, you should be able to troubleshoot most of the problems that arise. The key is to make sure you understand the concepts first.

That being said, here are the most common issues I’ve seen my students have when working on their motors:

1) They strip the wrong part of the coil.

1.a) Most often they forget that they are supposed to strip only the underside of the wire on the arms of the coil. They mistakenly strip the whole wire. This could cause the coil not to spin properly and also in some cases to over heat.

1.b) They strip the bottom of the wire when the coil is lying down. Make sure you are stripping the underside of the coil when it is oriented as an upstanding “O.” Ask yourself, will the charges flowing through this wire get a push in the right direction according to the rules set out in the second video?

2) The coil isn’t symmetrical. Before you connect up the power, the coil should spin quite well with just a little push. If the arms are off center this can be a problem.

3) The coil isn’t wound tightly enough. The coil should be very tight and neat.

Also you could be using the wrong type of wire. It needs to be thin, but also insulated. I’ve had good luck with this wire. http://www.radioshack.com/product/index.jsp?productId=2036277

If something isn’t working ask yourself “why?” You should have enough information to figure out the answer. After all, that’s half the fun. I hope that helps.

Electricity & Magnetism Hand Rules (part one)

by David Colarusso - February 25th, 2007

Electricity and magnetism are intimately connected. Explore their relationship in this short explanation of hand rules.

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What is the magnetic field? (Introducing the Tabletop Explainer)

by David Colarusso - February 18th, 2007

On Friday I mentioned that I was at work on a video blog revolving around simple science questions. Well, here’s the inaugural episode. Right now I’m posting the videos on YouTube and embedding them here. However, I may look into hosting them from my site at some point seeing as how I still can’t access YouTube from school. The current YouTube description reads “Quasi-weekly answerers to science questions, along with brief lessons and ideas for teachers and students.”

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