Announcements. Example. Find the equivalent capacitance of the combination in the figure below. Assume that C 1 = 4 µF, C 2 = 4 µF, and C 3 = 2 µF. What is the equivalent capacitance of the whole system? 10 m F C) 4 m F 1 m F D) 2.5 m F. Example.
Find the equivalent capacitance of the combination in the
Assume that C1 = 4 µF, C2 = 4 µF, and C3 = 2 µF.
In the figure below the battery has a potential difference of 10 V
and the five capacitors each have a capacitance of 12 µF.
What is the charge on capacitor C1?
What is the charge on capacitor C2?
Flux is proportional to the charge
More General formulation:
The integral of the
electric displacement equals the charge
When a dielectric is placed inside a capacitor, it is polarized
That is the dipole moments of polar molecules partially align
Nonpolar molecules have dipoles induced and partially aligned
Surface charges are created and fields generated (e. g. induced) which
lowers the field inside the capacitor, and hence reduces the potential
difference and raises the capacitance.
We say there is an energy density,
Note: the final energy density does not
depend on anything to do with the capacitor!
This energy density is actually the energy density of an
electric field. This is why we care about the energy density.