Calculate the current density needed to `levitate' a copper wire in the earth's magnetic field (that is, the current required for the lorentz force on the wire to be equal to its weight). assume that the wire is at the magnetic equator where the field is horizontal with magnitude 10-4 tesla. take the density of copper to be 8.9 g cm3 .
(b) calculate the power dissipated in the wire per unit volume. will the wire become hot? the resistivity of copper is 1.7 x 108 ω.m and the heat capacity of copper is 385 j kg-1 k -1 .
i have part (a) i just need part (b)
answer to part (a) is j=8.73x10^8 a/m^2.