Given = 2 ÂμF, = 6 ÂμF, and = 3 ÂμF, what is the total capacitance of the circuit
in the figure above?First, we find the equivalent capacitance of and. Since they are in parallel, =
+ = 8 μF. Then is given by:Dielectrics
One way to keep the plates of a capacitor apart is to insert an insulator called a
dielectric between them. A dielectric increases the capacitance. There is an electric field
between the plates of a capacitor. This field polarizes the molecules in the dielectric; that
is, some of the electrons in the molecules move to the end of the molecule, near the
positive plate:
The movement of electrons creates a layer of negative charge by the positive plate and a
layer of positive charge by the negative plate. This separation of charge, in turn, creates
an electric field in the dielectric that is in the opposite direction of the original field of the
capacitor. This reduces the total electric field: