This is actually an equation showing relation in between Potential difference(V), Intensity of Electric Field(E) and the distance between two parallel conducting plates.
Consider a system of two conducting plates with one plate having positive charge and the second plates induces negative charge in it.Hence the direction of Electric field intensity inside the plates will be shown from positive plate to negative plate.
Suppose the distance between two plates be given by “d” and the Electric field intensity be “E”.
As we know the expression of Electric field is given as
K is Dielectric constant of the medium between two plates
q is charge accumulated on the plates
d is distance between two conducting plates
Now,the electric potential is given as
Putting this value in eq(1),we get
Hope you got that!!!