A circular metal plate of radius 0.2 m has 1010 excess electrons uniformly distributed over its surfaces. What is the magnitude and direction of the field just outside the plate near its center?
E = kQ/r2
The Attempt at a Solution
Starting with E = kQ/r2,
I solved for Q: (1010) (1.60 x 10-9 C)
= 16 C
Plugging into the equation for E:
E = (16 C) (9.0 x 109 N m2/C2) / (.02 m)2
I end up with a really high value of 3.6 x 1012 N/C.
However, I know this is wrong because I should end up with a value of around 720. What am I doing wrong?
For direction, I know the electron will move towards the plate.