1. Capacitors and dielectrics
Introduction of a dielectric  capacitance increases
With battery connected potential difference is fixed and maintained, charge increases. In other words, energy increases => dielectric is pushed out
When the battery is not connected, charge stays the same, the energy decreases  dielectric is pulled in.

2. Videos
How flash works

3. hitt What is the equivalent capacitance?
a. 38 F b. 12 μF c. 20 μF d. 6 μF

4. Problems to consider
The top serial combination has equivalent capacitance
C1 = 2μF the bottom is C2 = 4/3 μF. The total equivalent
Capacitance of the two in parallel is 2+4/3 = 10/3 μF.
The charge on the outside plates on top is 2x90 = 180 μC
=Q6 = Q3
On the bottom outside plates is 4/3x90 = 120 μC = Q2 = Q4
V6 =potential difference across the 6 μF cap = Q/C = 30V
V3 = 60V
V2 = 60V and V4 = 120/4 = 30V 2
4/3

5. Problems

6. Problems

7. Problems

8. Problems
Here there are two capacitors in parallel

10. =
An infinite sequence of capacitors, each equal to C. Find the equivalent capacitance S.
But watch… algebra-wise this is also described by the equation… Solve for S. =
If you just look at the first link, by replacing s in the last arm by C, its equivalent capacitance is 1.33C, a great guess for the whole thing

11. If the areas are A1 and A-A1.
C \muF, q = 28.8 \muC
C2 C24 = 12 \muF
C1234 = 3 \muF q =36 \muC