Four identical metal plates each of area A are separated mutually by a distance d and are connected as shown. Find the capacity of the system between the terminals A and B.

Explanation

Area of each plate of a capacitar `=A`
Distance between two parallel plate capacitors `=d`
Capacity of each parallel plate capacitar. `C=(epsi_0A)/(d)`

The equivalent circuit of the above fig is

The effective capacitance `C_("eff") `
`=(C)/(2)+C=(3C)/(2) " "[because C_s=(CxxC)/(2C)]`
`therefore C_("eff")=(3epsi_0A)/(2d)` .