Gauss' Law: Net Electric Field of Two Spheres

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Homework Statement


Two nonconducting spheres, of r1=3.0cm and r2=2.0cm, are placed of an x-axis. They have surface charge densities of +6.0mC/m2 and +4.0 mC/m2, respectively, on their outside surfaces. The center of sphere r1 is on the origin and the center of sphere r2 is 10 cm away. What is the net electric field at x=2.0 cm?



Homework Equations


E=kq/r2
Area=4pir2

The Attempt at a Solution


I noticed that x=2.0cm falls inside sphere r1 and that the Electric Field inside a sphere due to an outside charge equals 0. I think this is the answer but want to be sure.
 
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I do not think so! because they are non conducting spheres... so we can not ignore the effect of the second sphere, I guess! i will look it up more though...
 
The field inside a uniformly charged sphere is zero (the field of THIS sphere vanishes), but the field outside a uniformly charged sphere is the same as if all the charge was at its center (we can treat it like a point-charge on most regards)... You should get your answer easily!
 
Yeah I tried that before you told me and it was pretty easy and good to know the way i thought was right. I got -3.10x10^3 N/C because of the direction of the field
 
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