• a) Describe the results.
• b) Make up a rule for remembering the relationship between the direction of the current in a wire and the direction of the magnetism near the wire (i.e., when the current is up, the magnetic field . . . ). Anyone told your rule should be able to use it with success. Write your rule in your log. Include a sketch. (Hint: One of the rules that physicists use makes use of your thumb and fingers.)

Reflecting on the Activity and the Challenge
This activity has provided you with knowledge about a critical link between electricity and magnetism, which is deeply involved in your challenge to make a working electric motor or generator. The response of the compass needle to a nearby electric current showed that an electric current itself has a magnetic effect which can cause a magnet, in this case a compass needle, to experience force. You have a way to go to understand and be able to be “in control” of electric motors and generators, but you’ve started along the path to being in control.

Physics To Go
1. If 100 compasses were available to be placed on the horizontal surface to surround the current-carrying wire in this activity, describe the pattern of directions in which the 100 compasses would point in each of the following situations:

a) no current is flowing in the wire
b) a weak current is flowing in the wire
c) a strong current is flowing in the wire

2. If a vertical wire carrying a strong current penetrated the floor of a room, and if you were using a compass to “navigate” in the room by always walking in the direction indicated by the north-seeking pole of the compass needle, describe the “walk” you would take.