Find the equivalent capacitance between point a and b in the following arrangement of the plates .

Explanation

First of all number the plates as shown :

Now you see that plate 2 is being shared by plate 1 and 3 also plate 3 is being shared by plate 2 and 4 . So in the complete elaborate diagram plate 2 and plate 3 will appear twice . Start from a connect two plates 2 put 1 and 3 in front of them . Then connect 3 to point b and connect one more plate 3 . Then in front of 3 put plate 4 and then joint plate 4 and plate 1 as follows

You can clearly see here two capacitance are in series connected in parallel to another capacitor. So equivalent capacitance is `(C)/(2) + C = (3C)/(2) = (3)/(2) (epsilon_(0)A)/(d)`