gauss law problem
An infinite line of charge with linear density λ1 = 7.4 μC/m is positioned along the axis of a thick insulating shell of inner radius a = 2.8 cm and outer radius b = 4.2 cm. The insulating shell is uniformly charged with a volume density of ρ = -792 μC/m3.
Im confused in this one because it has two different charge densities. I need to find the electric field at a<r<b and just set it up without plugging in the values. i need to express my answer in rho a lambda r b and Eo
i know its EAs = Qen/E0 Im thinking it is E (4pir2)= [-rho*l(pir^2-pia^2)]+lambda*l]/Eo
im not sure if its right and i dont think so cause i dont know l