Question

1. Two circular parallel conducting plates, each of radius 6cm, are charged such that they carry equal but oppositely signed charges of +1nC and -1nC. The plates are separated by a distance of 30mm.
a. Find the electric field that exists outside the parallel plates.

b. Find the electric field that exists between the parallel plates

Answer 1

I know I am supposed to use the formula
\[E=Q/(A \epsilon _{0})\]

Answer 2

where eo = 8.854 x 10-12 F/m

Answer 3

but I dont know the difference between finding the electric field outside the parallel plates and between them and for finding the outside E, do I have to use the distance between the plates?

Answer 4

just add and subtract the value of electric fields as shown outside the plates and between the plates.

Answer 5

The electric field for an infinite charged plate is \[E=Q/A \epsilon _{0}\]Note that field is extends in both directions from that plate. That means the field on one side of the plate is \[E=Q/2A \epsilon _{0}\]Now using the drawing given by Rohitkhanna, you should be able to calculate the field between the two plates in your problem.

Answer 6

well thanks but I got a chance to ask my professor and he said that there is no electric field outside the parallel plates. In other words, it is zero.

so Rohitkhanan's drawing might be for the parallel plates before they come next to each other and the electric field disappears outside making is zero and there is an electric field only between the plates