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## Homework Statement

A circular metal plate of radius 0.2 m has 10

^{10}excess electrons uniformly distributed over its surfaces. What is the magnitude and direction of the field just outside the plate near its center?

## Homework Equations

E = kQ/r

^{2}

## The Attempt at a Solution

Starting with E = kQ/r

^{2},

I solved for Q: (10

^{10}) (1.60 x 10

^{-9}C)

= 16 C

Plugging into the equation for E:

E = (16 C) (9.0 x 10

^{9}N m

^{2}/C

^{2}) / (.02 m)

^{2}

I end up with a really high value of 3.6 x 10

^{12}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.

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