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## Homework Statement

An atom that has Z protons, each with positive charge of magnitude e, reside in the nucleus at the center, surrounded by a uniformly distributed spherical cloud of radius R consisting of Z electrons, each with negative charge magnitude e, centered on the nucleus e. Use Gauss's Law to determine an expression for the electric field as a function of r, the distance from the center of the atom.

(1) Find the value of electric field for r<R (magnitude + direction)

(2) Find the value of electric field for R>r (mag + dir)

(3) If the atom were ionized, such that it was deficient by one electron, what would be the new expressions for the regions r<R and r>R

## Homework Equations

Gauss's Law: Integration of E dA = Q/eo

E = kq1q2/r^2

## The Attempt at a Solution

(1-2) I treated this problem as a hollow sphere

The electric field is zero inside a conducting sphere.

The electric field outside the sphere is given by: E = kQ/r2, just like a point charge.

(3) This one I have no idea......

Thank you for your help