Log on to http://phet.colorado.edu/simulations/electrichockey/webstart.jnlp.

Force a charge around multiple physical barriers and into the net using fixed charges.

1. Click the RESET and CLEAR buttons and select Difficulty: 3. Your goal is to get the black positive charge around the physical barriers and into the net.
2. Add and move charges by clicking and dragging each charge.
3. Click the RESET button.
4. Release the black positive charge by clicking the START button. Note the relationship between the charge's path and the strength and direction of the electric field along its path.
5. Repeat steps 2 through 4 after each trial is complete, attempting to get the black positive charge into the net.
6. When have scored a goal, note the number of tries it took you and any observations you have about the process and what you learned.

Difficulty 3 with Larger Mass - Force a larger mass charge around multiple physical barriers and into the net using fixed charges.

1. Increase the mass of the black positive charge to 100 by sliding the slide control for mass all the way to the right.
2. Click the RESET button. Do not clear the screen of your charges from the last successful try.
3. Release the black positive charge by clicking the START button. How did the larger mass affect the trajectory of the black positive charge?
4. Add and move charges by clicking and dragging each charge.
5. Click the RESET button.
6. Release the black positive charge by clicking the START button. Note the relationship between the charge's path and the strength and direction of the electric field along its path.
7. Repeat steps 4 through 6 after each trial is complete, attempting to get the black positive charge into the net.
8. When have scored a goal, note the number of tries it took you and any observations you have about the process and what you learned, especially the effect of a larger mass.

REPORT ON YOUR OBSERVATION