Question

some quantity of charge is distributed
uniformly over the surface of a thin walled hollow sphere of
radius 0.5m. The magnitude of the field is 4.0×10^2N/C at a
distance of 6.0m from the center of the sphere. Calculate
the quantity of charge on the sphere .

Answer 1

Gauss' Law applies. Outside the sphere, you can consider the field as if it were a point charge at the center of the sphere.

E=kQ/r^2 solve for Q