Procedure

• Open the web browser and navigate to the websitehttp://phet.colorado.edu/en/simulation/efield. Click the green button that says "Run Now!"

• You should be presented with a box that has a bunch of dots in it. Clicking the "add" button will drop a charged particle into the box of dots. When this happens, what do the dots become? The dots become arrow and they are going straight to the ball.

• Clicking on the charged particle and dragging it will set it in motion. What happens to the arrows as the charged particle moves around? Pause the motion of the particle at any point and add a cropped screen shot or cell phone photo of what you see, in addition to a written description, here:

The "field" of arrows you see in the simulation is a visual representation of the electric field. The electric field measures the electric force on a tiny test charge particle at any given point in space surrounding another point charge. The long arrows near the point charge show that the electric force is large, the small arrows far away show that the electric force is small far away from the charge.

Using the "Properties" button on the simulation you can vary the charge and the mass of the charged particles. You can put multiple charged particles on the same field, and any properties you change will only affect the next particle you add. Make the changes suggested in the following steps and record your observations. Please take a screen shot of your simulation screens once they have the requested features and paste those screen shots into this document. In this simulation, changes only affect the NEXT charge you add. Once you change a setting, you must add a new charge, and this new charge will have the desired settings.

• Change the magnitude of charge for the charged particle. How does that affect the electric field?

• Change the sign of the charged particle (i.e., if it's positive, make it negative). How does the change in sign affect the electric field? A sketch would be quite helpful here.

• How do two positively charged or two negatively charged particles behave around each other? What affect does this have on the electric field?

• How do two oppositely charged particles behave around each other? How does this affect the electric field?

• Does the mass of the charged particle have any effect on the electric field?