Question 1

Follow the instructions on page 7, using your Pie Plate Demonstrator to answer the following questions. In this experiment, we assume the foam plate has a positive charge when rubbed with paper towels.

Lift the pan away from the charged plate using the styrofoam cup. Briefly touch the rim of the pan to neutralize it. Place the neutralized pan on the plate and observe the tape rise. When the pan is on the plate, the rim of the plate has a (positive charge/negative charge). This means that (the pan base is negatively charged/ the pan base is positively charged) because the net charge on the pan is (positive/negative/zero). You know that this must be the case because as you lift the pan with the cup away from the plate, the tape on the rim goes down. This indicates that there is (a net charge on the rim/no net charge on the rim), therefore the pan is (positively charged/negatively charge/neutral/charged, but not able to determine the sign).

Question 2

Charging by Induction

Lift the pan away from the charged plate using the styrofoam cup. Briefly touch the rim of the pan to neutralize it. Place the neutralized pan on the plate and observe the tape rise. Touch the rim of the pan and observe the tape lower. Touching the rim of the pan while it's on the foam plate (neutralizes the pan, allowing electrons to move from your finger to the pan/neutralizes the pan, allowing electrons to move from the pan to your finger/gives the pan a positive charge, allowing electrons to move from the rim to your finger/gives the pan a negative charge, allowing the electrons to move from your finger to the pan). This leaves the base of the pan (positively charged/negatively charge/neutral, since the tape went down). Lifting the pan, the tape rises. This is caused by (positive charges on the base of the pan, which migrate to the rim/negative charges on the base of the pan, which migrate to the rim).

Question 3

Oscillating aluminum ball.

Neutralize the pan and then place it on the styrofoam plate. The tape will rise. Slowly bring an index finger closer to the ball and explain why the ball oscillates back and forth, hitting your finger and the rim? Your explanation should discuss:

• The sign of the charge on the rim at the start,
• The sign of the charge on your finger when placed near the charged rim,
• The sign of the charge on the ball after it hits your finger,
• The sign of the charge on the ball after it hits the rim,
• The behavior of the recording tape as the ball bounces back and forth
• The location of the initial charge on the rim as the ball bounces back and forth.

Question 4

Neon Bulb

Dim the room lights. Neutralize the plate and put it back on the charged Styrofoam plate. With the tape up, touch the free wire from the bulb while watching the electrodes inside the casing. The light produced may be weak so you may have to shadow the bulb to see the flash. Lift the plate, check that the tape rises again and touch the free bulb wire while observing the bulb. Without charging the Styrofoam, repeat placing the pie pan on and then off the Styrofoam plate, each time touching the free wire while observing which electrode lights.

For each case, state whether the light emanates for the electrode connected to the free wire or from the electrode attached to the rim. Based on the results of the previous step, explain how your results are consistent (or inconsistent with the sign of the charge on the rim as determined in steps 4-6 of the instructions, assuming the Styrofoam plate becomes positively charged when rubbed with paper towels.

Comment: There is no pie chart, this experiment was intended to demonstrate electrostatics using an aluminum pie pan.