1. The problem statement, all variables and given/known data A cylindrical conductor with a circular cross section has a radius a and a resistivity ρ and carries a constant current I. What is the ﬂow of energy into the volume occupied by a length l of the conductor? 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. 2. Relevant equations no 3. The attempt at a solution (first of all, sorry my bad english) I found it to be ρ I² l / π a² Now my answer for why can we think the flow as entering on the conductor is that the field energy is the cause of the increase of the thermal energy, and thus it must be equal each other. Is it ok?