®
ES-9080B
012-07227G
Basic Electrostatics System
15
• Before inserting the charged disk in the ice pail, make sure you’re touching the
grounded shield.
4.
Carefully insert the charged object into the ice pail, all the way to the lower half of the
pail, but without letting it touch the pail. Note the electrometer reading.
5.
Remove the object and again note the electrometer reading. If the handle never touched
the pail, the reading must be zero.
Question: Why was there a potential difference between the pail and the shield only while
the charged object was inside?
6.
Push the ZERO
button to remove any residual charge. Now insert the object again, but let
it touch the ice pail. Make sure your students know and see that you are touching the ice
pail with the charged disk this time.
7.
Remove the object and note the electrometer reading.
Questions: Why is there now a permanent potential difference between the ice pail and the
shield? Where did the charge on the ice pail come from?
8.
To show that the charge gained by the ice pail was lost by the disk, ground the ice pail to
remove all charge. Press the ZERO button to remove residual charges from the
electrometer. Insert the charge producer again into the ice pail. Does any charge remain on
it?
Procedure 1B: Conservation of Charge
1.
Starting with initially uncharged charge producers, rub the blue and white materials together.
Follow the general procedure for charging listed in part 1A, except that in this case you must
keep both producers from touching anything else after charging. (Keep them in your hands,
without letting them touch each other or the ice pail.)
2.
Use the Faraday Ice Pail to measure the magnitude and polarity of each of the charge
producers by inserting them one at a time into the ice pail and noting the reading on the
electrometer.
Questions:
What is the relation between the magnitude of the charges?
What is the relation between the polarity of the charges?
Was charge conserved in the demonstration?
3.
Completely remove all charge from the charge producers by grounding them. Do not
forget to also remove any stray charge from the necks and handles.
4.
Insert both charge producers into the ice pail and rub them together inside the pail. Note
the electrometer reading. Do not let the charge producers touch the pail.
