Question

Two parallel plates that are initially uncharged are separated by 1.2 mm. What charge must be transferred from one plate to the other if 11.0 kJ of energy is to be stored in the plates? The area of each plate is 19.0 mm2.

Answer 1

Answer: 55.52 *10^-6 C= 55.52 μC

Explanation: In order to solve this question we have to take into account the following expressions:

potential energy stired in a capacitor is given by:

U=Q^2/(2*C)  where Q and C are the charge and capacitance of the capacitor.

then we have:

Q^2= 2*C*U=

C=εo*A/d where A and d are the area and separation of the parallel plates capacitor

Q^2=2*εo*A*U/d=2*8.85*10^-12*1.9*10^-5*11*10^3/(1.2*10^-3)=

=55.52 *10^-6C