Demos: 6B-10 Forces Between Parallel Conductors
The repulsion/attraction between two parallel conductors carrying the same current in the opposite/same direction is demonstrated.
Directions: The current in the wires may be directed by use of the reversing switch in the circuit. Determine in advance which position causes repulsion and which causes attraction. For better visibility use light projection to display the shadows on the wall or use the camera projection system.
Suggestions for Presentation: Ask the students to think about the right-hand rule regarding the direction of the magnetic field around a current-carrying wire. Then focus on the region between the wires and ask how the fields interact at this position--add or subtract? Do the same with the region outside the wires (in the same plane). How does the addition and subtraction of fields contribute to the direction of the resultant force?
An alternative is to perform the demonstration first and have the students account for what happened.