# Magnetism Lab 19

Topics: Magnetic field, Electromagnetism, Magnet Pages: 6 (1318 words) Published: October 14, 2012
Magnetism – Lab 19

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 repeat the steps above after you’ve let the compass stabilize.

The results are the same.
8. 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.)

9. 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.

The Red lead faces the left side of the coil and as the compass is moved towards the upper center part of the coil, the compass is parallel to the coil. As the compass is moved towards the right side, the white lead ends up facing the coil.

10. 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.

The White lead faces the left side of the coil and as the compass is moved towards the upper center part of the coil, the compass is parallel to the coil. As the compass is moved towards the right side, the Red lead ends up facing the coil.

11. How many complete rotations does the compass needle make when the compass is moved once around the coil? One complete rotation.

12. Use the voltage slider to change the direction of the current and repeat the steps above for the coil after you’ve let the compass stabilize.

Same results.

13. Based on your observations, summarize the similarities between the bar magnet and the coil.

The Bar magnet and the Coil experiments have the same results. In both, the compass lead is attracted in one side of the coil or magnet and it rotates 180 degrees by the time it gets to the other side.

14. What happens to the current in the coil when you set the voltage of the battery to zero?

The current stops flowing in the coil.

15. What happens to the magnetic field around the coil when you set the voltage of the...