Name: ______________________
Partner: ________________________ Date: _______________
SNC 1P- Static Electricity and the Pithball Electroscope
Background Information
In class we have been learning about the atom, laws of electric charge and static electricity. Can you
remember what part of the atom can move? What about the laws of electric charge? What type of
charging occurs when two insulators rub together?
What part of the atom moves? ____________________________
Laws of Electric Charge:
1.
2.
3.
4.
When two insulators rub together charging by ____________________ occurs.
When an object becomes charged by friction, it can then charge other objects by touching them. We call
this type of charging, charging by contact. In today’s lab you and your partner will use a pithball
electroscope to investigate how charging by contact occurs and draw diagrams to explain your
observations.
Purpose: To investigate how a pithball responds to a charged ebonite rod.
Materials:
__ Pithball electroscope
___ Ebonite rod
___ fur
Procedure:
___
___
1. Place a check mark in the space provided as you complete each step of the lab
___
3. Carefully + gently touch the pithball (do not pull on it) with your hand to ground any surplus
2. Obtain your equipment and find a place on the lab benches to work
charges. This leaves the pithball neutral.
___
4. Place the neutral ebonite rod near the neutral pithball
What happened? (Observation) * use a full sentence*
________________________________________________________________________________
________________________________________________________________________________
___
5. Next, rub the ebonite rod on the fur for 30 seconds. Place it near the pithball. Record your
immediate observations.
What happened? (Observation) * use a full sentence*
________________________________________________________________________________
________________________________________________________________________________
___
6. Pull the ebonite rod away and then bring it into contact with the pithball. Record your
observations.
What happened? (Observation) * use a full sentence*
________________________________________________________________________________
________________________________________________________________________________
___
7. Pull the ebonite rod away and then bring it back toward the pithball. The result should now
be different from the result in step #6.
What happened? (Observation) * use a full sentence*
________________________________________________________________________________
________________________________________________________________________________
Discussion Questions
1. Read your observation for Step 4. State the Law of Electric Charge that explains this observation.
_____________________________________________________________________________________
_____________________________________________________________________________________
2. When the ebonite rod was rubbed on the fur what type of charging occurred? _________________
3. Using the electrostatic series, determine what material has a stronger hold on electrons.
Stronger hold on electrons: ___________________________________
4. After rubbing, what was the final charge on each object:
a) Final charge on Ebonite Rod:_______________________
b) Final charge on Fur: _____________________________
5. Use the shapes below to show the final charges on the fur and ebonite rod after being rubbed
together.
Ebonite Rod
Fur
6. Read your observation for Step 5. State the Law of Electric Charge that explains this observation.
_____________________________________________________________________________________
_____________________________________________________________________________________
7. Read your observation for Step 6. State the Law of Electric Charge that explains this observation.
_____________________________________________________________________________________
_____________________________________________________________________________________
8. When the ____________________(charge on ebonite rod) ebonite rod touches the neutral pithball
the pithball becomes _________________________ (final charge on pithball).
9. Use the shapes below to show what happened when the charged ebonite rod touched the neutral
pithball. Use arrows to show the movement of charge.
Charged Ebonite Rod
Neutral Pithball
Marking Scheme
Sections
Level 1
Minimal
requirements are
met
Level 2
Some of the
requirements
are met
Level 3
Most of the
requirements are
met
Level 4
All of the
requirements
are met
Weight
Inquiry
Observations are linked to
Laws of Electric Charge
(questions 1, 6, 7)
Charging by Friction
- understanding demonstrated
clearly (questions 2-5)
Charging by Contact
- understanding demonstrated
clearly (questions 8 + 9)
/3
/6
/4
/13
Overall Inquiry
Communication
Background Information
section is completed with
details
Observations are recorded in
full sentences
Diagrams are clear and show
charges evenly distributed
/2
/3
/2
/7
Overall Communication
LAB MARK
/20