1. The problem statement, all variables and given/known data In a sphere of radius R, the charge density varies as [tex]\rho[/tex](r) = BrN. There is no charge outside the sphere. B and N are constants. a.) Find the charge enclosed in a sphere of radius r<R. 2. Relevant equations [tex]\rho[/tex]=dq/dv 3. The attempt at a solution I integrated [tex]\rho[/tex](r)(4[tex]\pi[/tex]r2dr) and got q=(4[tex]\pi[/tex]BrN+3)/(N+3) + C. Is this right? If so, would it be correct to use the boundary condition; @ r=R, q=0 in order to solve for C? It doesn't sound right because there must be charge at the surface?