I have a conceptual question. I have two physics books that say "In a common iron nail, the domains are randomly oriented. When a strong magnet is brought nearby, two effects take place. One is a growth in size of domains that are oriented in the direction of the magnetic field. This growth is at the expense of domains that are not aligned. The other effect is a rotation of domains as they are brought into alignment." Can anybody explain why the domains aligned with the magnet get bigger? I understand the second effect. But the first effect I can't figure out, and neither book offers an explanation. Any help would be appreciated (I have to teach this subject this week and really want to know!). Thanks so much.