Activities and Homework for Friday, September 9.
[1] Notice that there are a few new "washer-type" disc magnets in your kits. Yes, yes, you can use them to play little levitation games by putting them on a pencil or pen. Feel free. But beyond this, they have a few new features:
(1) They are clearly not metallic, even though they are permanent magnets. What type of material do you think they are made of?
(2) The other disc magnet that we have used has its poles on its edge. Use the magnaprobe {or a compass} to determine where the poles of your new magnets are.
[2] Get a large sheet of paper, and tape it to your table, as indicated in Experiment 6.6 on page 296. Place your two bar magnets on the paper and tape them in place, as indicated. You are now going to map the magnetic fields of these magnets, but you're going to do it in a much slicker way than they suggest in Experiment 6.6 (that is, you won't be using a huge number of compasses). Get a Magnaprobe from John, and he will explain to you how to make the field mapping. After you have finished mapping your field lines, put arrows on them pointing from North poles to South poles.
[3] Using a new sheet of paper, map the magnetic field lines for a single metallic disc magnet (once again, tape the magnet to the paper to keep it from moving). Again, put arrows on the field lines.
[4] Complete Experiment 8.1 on page 305. When you do this experiment, use your compass to test the paper clip. Additionally, make sure that there are no other magnets anywhere near the compass and paper clip when you do your testing.
[5] As Homework for Tuesday, September 13, do Exercise 5.6 on p. 292 and Exercise 7.6 part A on p. 304. In Exercise 7.6, they refer to a "dip needle". The magnaprobe that you have used is essentially a dip needle - the point is that it is free to point in any direction, including up and down. Even though we have not done the Part C that they refer to, you can still do this problem by imagining that the Earth has a large bar magnet imbedded in it.