Two long, charged, thin-walled, concentric cylinders have radii of 3.0 and 6.0 cm. The charge per unit length is 6.50 10-6 C/m on the inner shell and -8.00 10-6 C/m on the outer shell.
(a) Find the magnitude and direction of the electric field at radial distance r = 4.0 cm from the common central axis. (Take radially outward to be positive.)
(b) Find the magnitude and direction of the electric field at r = 7.6 cm, using the same sign convention.