Oct 26th, 2010
In this lab we will investigate some properties of electric charge, conductors, and insulators using everyday objects.
A charged object is any object that has an excess of negative or positive charge. Most objects are neutrally charged and we don’t normally experience their charge properties. Rubbing objects together and transferring some charge from one to the other is one way to create charged objects. Like charges repel each other and unlike charges attract each other. The charge in a conductor is free to move around, while the charge in an insulator stays where it is. When two conductors come in contact, they share their charge with each other.
Pie Plate: Clear a space on your work bench to make it easier for the following steps. Vigorously rub one side of the Styrofoam piece provided with a piece of fur. Do not touch this side; instead place it immediately down on the cleared work bench. Pick up the pie plate using the Styrofoam cup as a handle and place it on the Styrofoam. Do not directly touch the pie plate when doing this. Slowly the pie plate with your index finger. Using the Styrofoam cup as a handle, pick up the pie plate and touch the metal side with your index finger again. Repeat these steps a few more times, all results should be identical.
Make sure the electroscope needle is nearly vertical. Hold the charging plate with your fingers if it doesn’t appear vertical. This nearly vertical position is called the “charge neutral” position. Rub a rod provided for you with fur and bring the rod near the top of the electroscope without touching it. The electroscope needle should move. Keeping the rod in place, hold the charging plate with your thumb and fingers. Remove the rod and your hand. The needle should be in the same position as when you had only the rod there. This is called “permanently charged”. Touch your fingers to the plate