PHYSICS electrostatics

For uniform electric field,By E = V/d

V is the potential difference between the two plates

d is the separation of the two plates

E is the electric field between the two plates

Now, because Q = CV, where C is the capacitance of the two plates

We have C = Q / V

Now, C = ε0A / d

Combing the equations, we have E = Q / ε0A

where Q is the charge on the plates

A is the overlapping area of the plates

ε0 is the permittivity of vacuum

So, 55 = Q / (8.85 X 10-12)(1.0)

Charge on the plates, Q = 4.87 X 10-10 C

by Guass Law, (let E be electric field due to one plate only)
construct a small surface on a plate
2EA= Q/eo

As the two plate are in opposite charge
the field inside is 2E
hence total charge of one plate Q = 2EAeo= 55 * 1 * permittivity

Note that , the bothe calculation has an assumption that the field lines between plates is prependacular to each plate , so the field strength is indenpendent of the distance ( by guass law)