Consider the following arrangement of four parallel plates with plate area A each. The separation between each consecutive plate is d. The leftmost and rightmost plates are connected by a metal wire. Calculate the effective capacitance between points P and Q.

Explanation

We can first mark the faces of plates which are used as capacitor plates, with a number and then we can convert the arrangement into its equivalent schematic diagram using the usual symbol of a capacitor.

We can arrive at the following schematic diagram for the above given arrangement of plates as follows:

The capacitance of each capacitor in above case is
`C=(epsilon_(0)A)/(d)`
The set of two similar capacitors in series is connected in parallel with similar capacitor and net capacitance can be written as follows:
`C_(eq)=C+(C )/(2)=(3)/(2)C=(3)/(2) (epsilon_(0)A)/(d)`