Question

Two closely spaced circular disks form a parallel-plate capacitor. Transferring 2,908,962,723.33 electrons from one disk to the other causes the electric field strength to be 874,940.74 N/C. What are the diameters, in mm, of the disks?

Answer 1

For this question, we are first going to need to find the charge on the plate

We can do that using the amount of electrons per plate

q = Ne = (2.9 x 10^9)(1.6 x 10^-19) = 4.654 x 10^-10 C

Now that we have the charge, we can find Area with

`E=(q)/(A\epsilon_0)`

874940.74 = 4.654x 10^-10/A(8.85x10^-12)

A = 6.0108 x 10^-5 m^2

A = pi(d^2)/4

d = 0.00874 m = 8.748 mm