Physics for the Inquiring Mind [Phys 105]                   Fall 2005 Exercises and Homework for Tuesday, September 13. [1] Determine whether the nail in your box is magnetized.  How can you tell if it is? [2] You have two small coils of wire (held together with tape) in your kit.  Have a group member wrap one of these around your nail, leaving a bit of the wire free at each end of the wrapping.  Another group member should wrap the other coil around the plastic stirrer in the same manner. [3] Using your alligator clips, hook the two sides of your battery pack to the two ends of the wire wrapped around the nail.  There will now be current flowing through the wire. [4] Is your nail magnetized now?  If so, where are its poles? [5] Switch the two connections from the battery.  Does this change the position of the nail's poles? [6] By wrapping your wire around this nail, you have made an electromagnet.  Is your electromagnet strong enough to pick up a paper clip? [7] When you disconnect the battery pack from your wire, is the nail still able to pick up a paper clip?  What does this mean? [8] One of the drawings below is a correct representation of your electromagnet, and one is not.  Which one shows the correct relationship between the north and south poles and the direction in which the nail is wrapped? SHAPE  \* MERGEFORMAT [9] Now connect your battery to the coil wrapped around the plastic stirrer.  Does this coil behave like a permanent magnet, or is the nail's presence necessary in order to observe magnetic effects? [10] As homework for Thursday the 15th, do Exercise 2.2 on p. 534 (Volume II) of McDermott.