X and Y are large, parallel conducting plates closed to each other. Each face has an area A. X is given a charge Q. Y is without any charge, points A, B and C are as shown in figure.

As X is given a charge +Q, it is distributed equally on both surfaces because another uncharged plate Y is placed in front of the charged sheet X. An equal and opposite charge $-\frac{Q}{2}$is induced on inner surface and $+\frac{Q}{2}$ on outer surface of Y.

Charge density, ${\mathrm{\sigma }}_{\mathrm{A}}=\frac{\mathrm{Q}}{2\mathrm{A}}$

So, the electric field on both sides of A and B of the plate X is,

$E_A=E_B=\frac{\sigma }{{\in }_0}=\frac{Q}{2A{\in }_0}$

 and also,  ${\mathrm{E}}_{\mathrm{C}}=\frac{\mathrm{Q}}{2\mathrm{A}{\in }_0}$

$\therefore {\mathrm{E}}_{\mathrm{A}}={\mathrm{E}}_{\mathrm{B}}={\mathrm{E}}_{\mathrm{C}}=\frac{\mathrm{Q}}{2\mathrm{A}{\in }_0}$

The direction of $E_A,E_B,E_C$ Are shown in the figure