Question

Find equivalent capacity between `X` and `Y`
.

Answer 1

Let us give numbers to the four plates. Here `X` and `Y` are connected to the positive and negative terminals of the battery (say),

Here the arrangement can be represented as the grouping of two identical capacitors each of capacity `(in_(0) A)/(d)`. The arrangement will be as shown

Now the equivalent capacitance between `X` and `Y` is.
`C_(XY)=(C+C)=2C =2(in_(0)A)/(d)`.