Question

A bird is sitting on a horizontal power line and has a magnetic susceptibility χ_Bird = −8,8 · 10^(−6). How much electric current has to flow through the power line in order for the bird not to notice weight force? Think of the bird as a magnetic dipole, which lies 2 cm above the power line. The bird's density is ρ = 0,5g/cm^3.
Hint: Express the bird's magnetic moment through the reduced magnetization M and use cartesian coordinates for the magnetic field.

Answer 1