# Electric Field Hockey

Simulation Used: Electric Field Hockey from the PhET at the University of Colorado.
• Theory.

There are two types of electric charges. Similar charges repel and opposite charges attract. The magnitude and direction of the force between two charges is given by Coulomb's Law:
,
where the coefficient of proportionality k has a value of:

• Settings.

• Open the simulation Electric Field Hockey
• Select "Puck Positive", "Trace", and "Field" from the menu on the bottom of the simulation window.

• Practice Activities. Investigate how charged particles move in the present of other charged particles.

• Select level "Practice" from the bottom menu. There are no barriers on the screen.
• "Score a goal" by placing:
• One positive particle to interact with the positive puck.
• One negative particle to interact with the positive puck.
• Two negative particles to interact with the positive puck.
• Two positive particles to interact with the positive puck.
• One positive and one negative particles to interact with the positive puck.
• Results.
• By pressing simultaneously the ALT and PRTSC (printscreen) keys on your computer, take a snapshot of the active window.
• Paste it into an Image Editor. Save the file in .jpg or .png format. Note that .bmp files are much bigger than .jpg or .png.
• Possible image editors that can be used: Paint (on any Windows machine) ca be accessed from the Start Menu -> Accessories. You can also download the free GNU editor GIMP which has available versions for both Windows and Linux. For Macs, one possibility is OmniGraffle.
• The .jpg or .png files are your data and results. Save them and post them on Blackboard. Not recommended but an acceptable alternative is to print them out on paper.
• Here is an example of an unsuccessful trial with three barriers.

• Activity 1. No barrier, two negative and one positive charge.

• Keep the level "Practice" just as in the Practice Activities.
• Where should you place two negative and one positive charge so that you can score a goal with the positive puck?
• Once you succeed, save the picture in a .jpg or .png file. See the instructions above in the Practice Activities/Results sections.

• Activity 2. One barrier, no restrictions on charges.

• Change the level to "Difficulty 1" from the menu on the bottom.
• Place any number or kind of charges so that you can score a goal with the positive puck?
• Once you succeed, save the picture in a .jpg or .png file. See the instructions above in the Practice Activities/Results sections.

• Challenge Activities ( Optional/Extra Credit ) Score a goal with two or three barriers.

• Change the level to "Difficulty 2" from the menu on the bottom.
• Place any number or kind of charges so that you can score a goal with the positive puck?
• Change the level to "Difficulty 3" from the menu on the bottom.
• Place any number or kind of charges so that you can score a goal with the positive puck?