The electric field in aregion is radially outward and at a point is given by E=250r V/m [where r is the distance of the point from the origin] .Calculate the charge contained in a sphere of radius 20cm, centered at the origin.

As we know the flux through the sphere is not zero so we apply gauss law.
E.dS=Q/epsilon. As E varies integrate with limits from 0 to 0.2 m.
250rd(4∏r²)=Q/epsilon
250r x 4 x ∏ x 2 x rd(r) = Q/episilon
now integrating we get
200∏R³/3 x epsilon =Q
Plimits to get final Ans.