Physics
posted by Bruce on .
The electric field intensity at a point 2 meters from the surface of a uniformly charged conducting sphere is 1920 N/C. At a point 4 meters from its center, the electric field intensity is 3000 N/C.
a.) Determine the radius of the sphere. Determine the electric field intensity at a point:
(b.) 2m from its center,
(c.) 6m from its center, and
(d.) 4m from its surface.
Please help me.

outside the sphere, E=kq/r^2
E=kQ/(r+2)^2=1920
E=kQ/4^2=3000
kq=16*3000
1920=16*3000/(r+2)^2
solve for r
r = 4 sqrt (3000/1920)2 check that math.