1. "If iron shavings are placed in the N-pole end of a solenoid, what happens to them?"

The "quick" answer is ... they will arrange themselves so as to follow the magnetic field lines. Below I show a couple of pictures from Tipler (volume 2) that demonstrate what happens:

This figure shows the magnetic field lines in the vicinity of a solenoid. Notice that the field lines are very compact and nearly parallel inside the solenoid but much more widely spaced outside. In fact, they are very similar to the field lines one would get from a bar magnet. When iron filings are scattered near the solenoid:

they align themselves along the magnetic field lines. (Not a very good picture but the best I could do in a short time!

By the way, there is something wrong with Figure 29-10(a) on page 890 in Tipler ... can anyone see the "problem"? Please post your answer on the discussion forum.

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