1. More on capacitors
Unit 8.2

2. Comings and Goings Today Friday Next Week – SPRING BREAK !!
More on capacitors (READ THE SECTIONS IN THE TEXT KISTED ON THE WEBSITE.)
New WebAssign
Friday
Quiz
Finish the Unit
We could do a problem session at 12:30 if you want one.
Next Week – SPRING BREAK !!

3. On your return Monday- Wednesday Friday
8:00 AM Problem Session if you are interested
Finish Unit or start the next one.
Wednesday
EXAMINATION #2
Start or continue study of magnetism
Friday
No Quiz …Magnetism only..

4. More Stuff Last time we discusses the parallel plate capacitor.
Today we go a bit deeper into these devices.

5. Remember last time?
The plates of a parallel plate capacitor each have an area of 0.40 m2 and are separated by a distance of 0.02 m. They are charged until the potential difference between the plates is 3000 V. The charged capacitor is then isolated.
Determine the magnitude of the electric field between the capacitor plates.
A) 60 V/m
B) 120 V/m
C) 1.0 × 105 V/m
D) 1.5 × 105 V/m
E) 3.0 × 105 V/m

6. Today
We discuss combinations of capacitors and you will find out more about this in the unit.
Recall last time:

7. Single Piece of Metal. Not connected to anything
String them together …..
Single Piece of Metal. Not connected to anything - -
electrons
electrons
electrons

8. String them together ….. q -q q -q + + + + + + + - - + + + + + + +
Charge is the same for every capacitor in a series “string”

9. String them together ….. C1 C2 q -q q -q + + + + + + + - -
Wires are equipotentials … sort of.

10. Two ways to go to the same place!
C C2
V V2
q q q q - - VT

11. Rule of adding series capacitors

12. Parallel is Easier! VT

13. Determine the equivalent capacitance between A and B for the group of capacitors in the drawing. Let C1 = 14 µF and C2 = 5.0 µF.

14. UNITS
A capacitor which acquires a charge of 1 coulomb on each plate with the application of one volt is defined to have a capacitance of 1 FARAD
One Farad is one Coulomb/Volt

15. WORK TIME!