Demo: Magnetic Field Projector
Joyce Gridley
Leonard Freise
Lane Matheson
Objective: Observe the magnetic field around a current carrying wire and a solenoid.
Equipment:
· Plexiglass
· Two pairs binding posts
· Small gauge wire
· Large gauge wire
Construction:
Wire-- Use the large gauge wire that will maintain a rectangular shape. Connect binding posts to plexiglass. Drill two holes to accommodate the wire. Pass the wire from the binding post through the holes and back to the binding post. One edge of the wire should be in the middle of the plexiglass.
Solenoid—create 5-6 coils by winding the small gauge wire around a jar. Each coil should have 6 turns. On the plexiglass cut three side of a rectangle to create a slot. The width of the rectangle should be approximately equal to the diameter of the coil. Space the coils about 1 cm apart. Connect the ends of the coil to the binding posts.
Procedure:
Provide a current to the wire. Sprinkle iron filings around the wire. Tap plexiglass. Observe the field that is created. May use a compass to determine the direction of the field. Repeat for the solenoid.
Discussion:
The field around a current carrying wire should circle the wire. The direction of the field will change polarity if the polarity of the voltage is switched.
Questions for student:
1. Sketch the field around the wire.
2. Describe the spacing of the fillings as the distance from the wire increases.
3. What happens to the direction of the field if the polarity of the power supply is switched?
4. What electric phenomenon is this similar to?
5. Sketch the field within the solenoid.
6. What happens to the fillings near the ends of the solenoid?
7. What happens to the direction of the field if the polarity of the power supply is switched?
8. What electric phenomenon is this similar to?