Two very long coaxial metal cylinders have radii R1, R2. The space inside the first cylinder is characterized by the volumetric charge density "ro". The surface charge density on the second cylinder is "sigma". Points A, B, C are at distances ra, rb, rc from the axis of the cylinders. Determine the strength of the electric field at the indicated points, plot the dependence E= f(r). R1=8cm, R2=12cm, rho=-7,*710^-8 C/m^2, sigma=8.9*10^-7 degree, C/m^2, ra=4cm, rb=12cm , rc=25cm.