A long copper cylindrical shell of inner radius 4 cm and outer radius 7 cm surrounds concentrically a charged long aluminum rod of radius 1 cm with a charge density of 9 pC/m. All charges on the aluminum rod reside at its surface. The inner surface of the copper shell has exactly opposite charge to that of the aluminum rod while the outer surface of the copper shell has the same charge as the aluminum rod. Find the magnitude and direction of the electric field (in N/C) at points that are at the following distances from the center of the aluminum rod. (If the magnitude is zero, select "none" for the direction.) (a) 0.4 cm magnitude direction (b) 2.5 cm magnitude direction (c) 6.0 cm magnitude direction (d) 14 cm magnitude direction (e) 19 cm magnitude direction

A long copper cylindrical shell of inner radius 4 cm and outer radius 7 cm surrounds concentrically a charged long aluminum rod of radius 1 cm with a charge density of 9 pC/m. All charges on the aluminum rod reside at its surface. The inner surface of the copper shell has exactly opposite charge to that of the aluminum rod while the outer surface of the copper shell has the same charge as the aluminum rod. Find the magnitude and direction of the electric field (in N/C) at points that are at the following distances from the center of the aluminum rod. (If the magnitude is zero, select "none" for the direction.) (a) 0.4 cm magnitude direction (b) 2.5 cm magnitude direction (c) 6.0 cm magnitude direction (d) 14 cm magnitude direction (e) 19 cm magnitude direction