Question

Two large metal plates of area 0.7m² face each other. They are 5.2 cm apart and have equal but opposite chargeson their inner surfaces. If the magnitude E of theelectric field between the plates is 53 N/C, what is the magnitude of the charge oneach plate? Neglect edge effects.

Answer 1

Given a parallel plate capacitor set up

Plate area A = 0.7 m²

El field between th plates, E = 53 N/C

Find charge Q on each plate.

We know the el field is related to surface charge density,σ = Q/A

In fact, E = σ/ε_o and so, σ =ε_o .E

Therefore, charge,

           Q= σ.A =  ε_o .E.A

              = 8.854x10^-12 x 53 x 0.7

              = 3.28x10^-10 C =328 pC