Find the equivalent capacitance of the combination shown in figure (31.10) between the points P and N.

Explanation

The `10muF and 20muF` capacitors are connected in parallel. Their equivalent capacitance is `10muF+20muF=30muF`. We can replace the `10muF` and the `20muF` capacitors by a single capacitor of capacitance `30muF` between P and. This is connected in series with the given `30muF` capacitor. The equivalent capacitance C of this combination is given by
`1/C=1/30muF+1/30muF` or, `C=15muF`.