Go to http://phet.colorado.edu/simulations/sims.php?sim=Magnets_and_Electromagnets and click on Run Now.
Part I:
1. 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.
The white lead of the needle faces the South part of the magnet in a perpendicular way. When the needle is facing the center of the magnet, the lead turns to a 90 degree angle, being parallel to the magnet. When the compass faces the North part of the magnet, the needle turns 90 degrees in the same direction until the red lead if facing towards the North of the magnet.
2. What do you suppose the compass needles drawn all over the screen tell you?
They represent the magnetic field.
3. How is the strength of the force/torque on the compass needle indicated?
By the speed when the direction is changed the faster the needle moves, the greater attraction force.
4. What are the similarities between the compass needle (magnetism) and a test charge (electricity)?
As like electric charges repel and opposite charges attract each other in electricity, like magnetic poles repel and opposite magnetic poles attract.
5. 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.
The Red lead of the needle faces the South part of the magnet in a perpendicular way. When the needle is facing the center of the magnet, the lead turns to a 90 degree angle, being parallel to the magnet. When the compass faces the North part of the magnet, the needle turns 90 degrees in the same direction until the White lead if facing towards the North of the magnet.
6. How many complete rotations does the compass needle make when the compass is moved once around the bar magnet?
One complete rotation.
7. Click “flip polarity” and