| Physics for the Inquiring Mind [Phys 105] Fall 2005 |
[1] There are a few different resistors in an envelope in your kit. Some of them are marked Yellow Violet Gold Gold, while others are marked Red Red Gold Gold. Determine, using any method that you wish, which type of resistor has the greater resistance.
[2] After you have finished Part [1], each group member should come up to the desk and grab a multimeter. This meter will be yours to keep, so be careful with it. You will need to use it for several experiments over the next few weeks, so be sure to bring it to class with you. For today's experiments, we will be using the multimeter as an Ammeter, a device that measures electrical current.
[3] Do Experiment 5.1 on p. 420 of your text. For the positive connection to the Ammeter, use the hole marked 10ADC. For the negative connection, use the hole marked COM. The dial should be set to 10A. If you want to be safe, make sure that your ammeter is disconnected from your circuit whenever you are changing its dial. If you have any questions about using the ammeter for the first time, chat with John to make sure you know how to use it. You have to be careful with ammeters!
[4] Based on your result from Part [3], predict the amount of current that will flow through a circuit containing the battery pack, two light bulbs, and the ammeter all in series. Use your ammeter to measure this current. Was your prediction correct?
[5] There is a green box marked P64012 in your kit. Open it and carefully remove the assembly inside. Use the red and black wires coming off of the assembly to attach it to your battery pack. See if you can get the armature to spin.
After you have gotten your armature to spin, try to figure out why it is spinning! Explain as clearly as you can why it is spinning, and describe the function of each of the components of your motor [your assembly is a very simple example of what is called a DC motor].
[6] As a reminder, as Homework for Friday, October 7, do Exercise 2.3 on p. 392, Exercise 3.4 on p. 401, and Problem 1.3 on p. 494, Problem 2.1 on p. 495, and Problem 2.2 on p. 495.