3. Select the simulation “Magnets and Electromagnets.” It is at this link http://phet.colorado.edu/new/simulations/sims.php?sim=Magnets_and_Electromagnets 4. Move the compass slowly along a semicircular path above the bar magnet until you’ve put it on the opposite side of the bar magnet. Describe what happens to the compass needle.
5. What do you suppose the compass needles drawn all over the screen tell you?
6. How is the strength of the force/torque on the compass needle indicated?
7. What are the similarities between the compass needle (magnetism) and a test charge (electricity)?
8. Move the compass along a semicircular path below the bar magnet until you’ve put it on the opposite side of the bar magnet. Describe what happens to the compass needle.
9. How many complete rotations does the compass needle make when the compass is moved once around the bar magnet?
10. Click “flip polarity” and repeat the steps above after you’ve let the compass stabilize.
11. Click on the electromagnet tab. Place the compass on the left side of the coil so that the compass center lies along the axis of the coil. (The y-component of the magnetic field is zero along the axis of the coil.)
12. Move the compass along a semicircular path above the coil until you’ve put it on the opposite side of the coil. Describe what happens to the compass needle.
13. Move the compass along a semicircular path below the coil until you’ve put it on the opposite side of the coil. Describe what happens to the compass needle.
14. How many complete rotations does the compass needle make when the compass is moved once around the coil?
15. Use the voltage slider to change the direction of the current
