Electric field just beyond surface of proton

[winterwind]

Homework Statement

If a proton is considered a uniform ball of charge of radius 1.0x10-15m, what is the
electric field just beyond its surface?

Homework Equations

Gauss's law?

The Attempt at a Solution

I followed a problem in the book that found an equation for the electric field of a uniformly charged sphere. I treated the proton as a uniform sphere of charge, so that the same equation could be applied.

The equation was E = (1/4piE0)(Q/r^2)

*E0 is constant 8.85 x 10^-12.

So I just plugged in charge of electron and radius r of the proton.

 

[Kurdt]

That looks fine. The result can of course be derived from Gauss' law. Remember that a proton has the same magnitude of charge as an electron but different sign.