Copper has volume susceptibility and density .

PHYSICS · Multi-part · Fermi University Physics · Electricity, Magnetism & Electromagnetism · Magnetic materials · Magnetic materials

The Boundary-Value Problem, Ch Diamagnetism, paramagnetism and magnetic susceptibility

Problem

Copper has volume susceptibility

\chi_m=-9.6\times10^{-6}

and density

\rho_m=8960\,\mathrm{kg\,m^{-3}}

. ((a)) Find the value of

B\,dB/dz

needed to levitate a small copper sample against gravity, taking

g=9.8\,\mathrm{m\,s^{-2}}

. ((b)) If a laboratory electromagnet supplies a field of

B=15\,\mathrm{T}

over the levitation region, find the field gradient

dB/dz

this requires, and comment on whether it is achievable on a laboratory bench.