Question

Two large metal plates of area 7.00 m.^2 face each other. They are 5.00 cm. apart and carry equal and opposite charges on their inner surfaces. If E between the plates is 78.0 N./C., what is the charge (in coulombs) on the plates? (Neglect edge effects.)

Answer 1

Solution:-

We have a parallel plate capacitor set up
Plate area A = 7.00 m2
El field between the plates, E = 78.0 N/C
Find charge Q on each plate.
Using the formula ? = Q/A
In fact, E = ?/?o and so, ? =?o .E
Therefore, charge,
           Q= ?.A =  ?o .E.A
              = 8.854x10-12 x 78 x 7.00
              = 4.83x10^-9 C