Homework 11

E&M Book 10.1, 11.1, 11.2, 11.3, 11.5, 11.7, 11.8, & 11.11

9) A superconducting DC power transmission line has been proposed that would carry 100 gigawatts of power at 200,000V over 1000km. The conductors would have a diameter of 25mm and be separated by a center to center distance of 75mm..

a) Calculated the force per meter between the conductors. (It would clearly preferable to use a co-axial line!)

b) Calculate the amount of energy stored in the magnetic field. Give your answer in kilowatt-hours. Remember that energy stored = 0.5 L I² and note that the self-inductance of a pair of parallel conductors of radius R separated by a distance D is .

10) A long solenoid, length L, has a single layer of turns, N per meter. By considering the energy stored in the coil, calculate the force between one turn and the next. Does this force tend to compress or expand the coil?