1. Presentation Outline Review Previous Day
Distribution of Charges in a Neutral Conductor (Homework)
Distribution of Charges in a Neutral Insulator (Homework)
Charging a Conductor by Touching
Inducing a Charge on a Conductor (Polarization)
Demo: Comb and paper / Rod and wood
Attraction between neutral conductor and charged object
Attraction between neutral insulator and charged object
Practice

2. Exit Quiz from Yesterday
What is the difference between a conductor and an insulator?
What kind of charge is not able to flow freely in a conductor?
If an object acquires a positive charge, did it gain protons or lose electrons? How do you know?
Why are cars safe in a lightning storm?
What does it mean for an object to be electrically polarized?

3. Let’s go back to the polarized neutral object…

5. If you could take a guess, would the rod and ball be attracted to or repelled by each other?
Why do you think so?

6. If you could take a guess, would the rod and ball be attracted to or repelled by each other?
Why do you think so?
Negative and Positive
are attracted!

7. If you could take a guess, would the rod and ball be attracted to or repelled by each other?
Why do you think so?
If we switched to a positively-charged rod, would they rod and ball attract or repel?
Negative and Positive
are attracted!

8. If you could take a guess, would the rod and ball be attracted to or repelled by each other?
Why do you think so?

9. A charged object will always attract a neutral conductor!
If you could take a guess, would the rod and ball be attracted to or repelled by each other?
Why do you think so?
This works for any polarized neutral conductor.
A charged object will always attract a neutral conductor!
Positive and Negative
are attracted!

10. So, charged objects attract conductors… What about attracting insulators?

11. So, charged objects attract conductors… What about attracting insulators?

12. So, charged objects attract conductors… What about attracting insulators?

13. So, charged objects attract conductors… What about attracting insulators?

14. Time for the “magic” wand!
So, charged objects attract conductors… What about attracting insulators?
Time for the “magic” wand!

15. Sticky Balloons

16. Charged Objects Also Attract Neutral Insulators!
When a charged object is brought near an insulator, the charges in the insulator can shift back and forth a little.
For example, a negatively charged plastic rod causes a slight shifting of charge within the molecules of the neutral wood.
The negative charges shift so that they are farther from the rod.
The wood has an excess positive charge near the rod and so feels an attraction.

17. Charged Objects Also Attract Neutral Insulators!
When a charged object is brought near an insulator, the charges in the insulator can shift back and forth a little.
For example, a negatively charged plastic rod causes a slight shifting of charge within the molecules of the neutral wood.
The negative charges shift so that they are farther from the rod.
The wood has an excess positive charge near the rod and so feels an attraction.

18. Charged Objects Also Attract Neutral Insulators!
Negatively Charged

19. Charged Objects Also Attract Neutral Insulators!
Negatively Charged

20. Charged Objects Also Attract Neutral Insulators!
Negatively Charged

21. Charged Objects Also Attract Neutral Insulators!
Negatively Charged

22. Charged Objects Also Attract Neutral Insulators!
Negatively Charged

23. Charged Objects Also Attract Neutral Insulators!
Negatively Charged

24. Charged Objects Also Attract Neutral Insulators!
Negatively Charged

25. Charged Objects Also Attract Neutral Insulators!
Negatively Charged

26. Charged Objects Also Attract Neutral Insulators!
Negatively Charged

27. Charged Objects Also Attract Neutral Insulators!
Ouch!
That’s gonna leave a scar!
Negatively Charged

28. In Conclusion… Charged Objects Attract Neutral Objects ALWAYS
Charged objects can “polarize” a neutral conductor—where the electrons can move freely—and become attracted to the neutral object.
Charged objects can “shift” the charges in a neutral insulator—where electrons cannot move freely—and become attracted to the neutral object.

29. Practice!