Answer D and E please

Part C A long, straight, solid cylinder, oriented with its axis in the z- direction, carries a current whose current density is J . The current density, although symmetrical about the cylinder axis, Obtain an expression for the current I contained in a circular cross section of radius r a AEd where a is the radius of the cylinder, r is the radial distance from the cylinder axis, and To is a constant having units of amperes. I(r) = Submit Request Answer Part D Using Ampere's law, derive an expression for the magnitude of the magnetic field B in the region r