Day 95: The Magnetic Field around a Wire

Yes! We're starting magnetism!

We started with a big charged plastic corrugated sheet that charges up nicely when we rub it against a certain student's curly hair. We put it next to a very strong magnet. What happened? How does that help us differentiate between magnetic interactions and electrostatic interactions?

Then, we got out the iron filings and sketched what they did near the magnets. They seemed to align to patterns we had seen before with electrostatics. There seems to be an analogy between magnetic fields and electric fields. We know, though, that any analogy isn't perfect, but it seems in our north-o-centric, up-o-centric, positive-o-centric world, we'd define the magnetic field in the direction a north pole would feel a force. (Question I didn't ask in class, but should've: where is the north pole that makes the Earth's magnetic field?)

After we sketched out some magnetic fields around magnets, we started looking at the magnetic fields around a wire. We knew there had to be a magnetic field since we saw the compass move when placed near a wire carrying a current. So we investigated it, and, in doing so, defined the right hand rule.