1. electrostatics
Movement of charges

2. Scientists figured this out Top of table
Most likely to lose/give up electrons
Ends up + charged
Bottom of table
Most likely to gain/take electrons
Ends up - charged

3. You can figure it out anything if…
You remember this…..
Like repels
Opposites attract
Electrons
Are transferred
Are free to move in and equalize charge in a conductor

4. Rubber rod/rabbit fur At start: both neutral
Process of charging: requires friction
Fur loses electrons : + charged
Rod gains electrons: - charged
Objects End up oppositely charged
_ _
_ _ _

5. glass rod/polyester fabric
At start: both neutral
Process of charging: requires friction
rod loses electrons : + charged
fabric gains electrons: - charged
Objects End up oppositely charged
_ _
_ _ _

6. Balloon / hair At start: both neutral
Process of charging: requires friction
Hair loses electrons : + charged
balloon gains electrons: - charged
Objects End up oppositely charged
_ _
_ _ _

7. Negative - rod/ neutral electroscope
No contact!
Neither object loses or gains electrons
Electrons are free to move
Want to get away from the negative charge on the neg rod, like charge
Move down the electroscope toward the foils
Knob + charge
Foils – charge: repel and angle outward
Remove rod, foils return to vertical
_ _
_ _ _ ++
+ +
_+ _+
_ +_+
_ _+ _+ _ _ _ +_+_

8. Positive +rod/ neutral electroscope
No contact!
Neither object loses or gains electrons
Electrons are free to move
Electrons attracted to positive rod, opposite charge
Move up the electroscope toward the knob
Knob -- charge
Foils + charge: repel and angle outward
Remove rod, foils return to vertical
+ + ++
_ _ + _+_ _ _ +_+_
_+ _+
_ +_+
+ +
+ +

9. Negative - rod/ neutral electroscope
Contact!
Charge is transferred to the electroscope
Electrons are free to move
Charge on the electroscope redistributes
Electrons move down the rod toward the foils
Knob - charge
Foils – charge: repel and angle outward
Remove rod, foils stay angled outward
Electroscope is charged -
_ _
_ _ _ ++
+ +
_+ _+
_ _ +_+
_ _+ _+
_ +_+
_ _+ _+ _ _ _ +_+_
_ _ _ _

10. Now the electroscope is negatively charged…..
What happens if we bring another charged object close to it?
A. foils remain the same, same outward angle?
B. foils repel even more, bigger angle?
C. foils repel less, smaller angle?
Approach with another negatively charged object?
A B or C? Draw and explain.
Approach with a positively charged object?
A B or C? Draw and explain

11. Positive + rod/negative electroscope
No contact!
Charge on the electroscope redistributes
Electrons move up the electroscope toward the knob, the + rod
Knob - charge
Foils – charge: still repel but angle is smaller
Remove rod, foils angle outward but return to larger angle
Electroscope is charged -
_ _ _ _
_ _ _ _
_ _ _ _
_ _ _ _

12. You touch the top of the negative electroscope
Contact!
Excess electrons move up the electroscope toward the knob and your hand
You are connected to ‘ground’ and provide a pathway for excess electrons to ‘escape’
Electroscope is now neutral
Will work with + electroscope too
_ _ _ _
_ _ _ _
_ _ _ _
_ _ _ _

13. Impossible or not?
Design an experiment in which the foils actually touch in the middle…