A thin, 1.52 m long copper rod has a mass of 52.4 g. What is the minimum current in the rod that will cause it to float in a magnetic field of 1.25 T? Answer in units of A.
At what distance from a long, straight wire carrying a current of 8.5 A is the magnetic field due to the wire equal to the strength of Earth's field, approximately 5.4 x 10-5 T? The permeabilty of free space is 1.25664 x 10-6 T x m/A. Answer in units of cm.