A cylindrical conductor with a circular cross section bas a radius a and a resistivity p and carries a constant current.
(a) What arc the magnitude and direction of the electric-field vector E at a point just inside the wire at a distance a from the axis?
(b) What are the magnitude and direction of the magnetic-field vector B at the same point?
(c) What are the magnitude and direction of the Poynting vector S at the same point? (The direction of S is the direction in which electromagnetic energy flows into or out of the conductor.)
(d) Use the result in part (c) to find the rate of flow of energy into the volume occupied by a length I of the conductor. Compare your result to the rate of generation of thermal energy in the same volume. Discuss why the energy dissipated in a current-carrying conductor, due to its resistance, can be thought of as entering through the cylindrical sides of the conductor.