(5%) Problem 21: A power line carries a DC current of I = 21 A in a direction = 41 east of magnetic north through an open field, in a location where the Earth's magnetic field is horizontal and its strength is B = 0.43 G. 17% Part (a) Calculate the magnitude of the magnetic force per unit length, F/1, in newtons per meter, exerted on the wire due to the Earth's magnetic field. F/1=5.92*104 F/1=5.920 10 N/m Correct! 17% Part (b) In what direction does the force on the wire act? Be aware that the magnetic field of the Earth actually behaves in the opposite manner you would expect from a physical magnet. The Earth's magnetic field lines point from the Earth's south pole towards the Earth's north pole. Up Correct! 17% Part (c) You decide to re-orient the wire to minimize the magnetic force acting on the wire. In which direction(s) could the current flow to get the minimum possible magnetic force on the wire? North, South Correct! 17% Part (d) In what direction(s) could you orient the current flow to maximize the magnetic force acting on the wire? East, West Correct! East 17% Part (e) In which of the directions that correctly answer part (d) is the magnetic force on the wire directed upward? Correct! 17% Part (f) If the wire is oriented so that the current flows in the direction you chose for part (e), what would the mass per unit length of the wire, , need to be for the magnetic force to balance the weight of the wire? Give you answer in units of grams per meter. g/m Grade Summary Deductions 0% Potential 100%