Like resistors, capacitors can be joined together in two basic ways: parallel and series. It should be obvious from the physical construction of capacitors that connecting two together in parallel results in a bigger capacitance value. A parallel connection results in bigger capacitor plate area, which means they can hold more charge for the same voltage. Thus, the formula for total capacitance in a parallel circuit is:
CT=C1+C2...+Cn ,
the same form of equation for resistors in series, which can be confusing unless you think about the physics of what is happening.
The capacitance of a series connection is lower than any capacitor because for a given voltage across the entire group, there will be less charge on each plate. The total capacitance in a series circuit is
CT={1{1C1}+{1C2}...+{1Cn}}
Again, this is easy to confuse with the formula for parallel resistors, but there is a nice symmetry here.
