A long metal cylinder with radius a is supported on an insulating stand on the axis of a long, hollow, metal tube with radius b. The positive charge per unit length on the inner cylinder is and there is an equal negative charge per unit length on the outer cylinder. (a) take V=0 at r=a. Calculate the potential V(r) from (1) r b. (b) To calculate the electric field at any point between the cylinders, that is a