A nickel rod is driven by an external field oscillating at

PHYSICS · Multi-part · Fermi University Physics · Electricity, Magnetism & Electromagnetism · Electromagnetic induction and alternating-current circuits · Electromagnetic induction and alternating-current circuits

The Boundary-Value Problem, Ch The quasi-static approximation, eddy currents and the skin effect

Problem

A nickel rod is driven by an external field oscillating at f=50 Hzf = 50\,\mathrm{Hz}. Nickel has conductivity σ=1.40×107 S m−1\sigma = 1.40\times10^7\,\mathrm{S\,m^{-1}} and, at the field amplitude used, an effective relative permeability μr=100\mu_r = 100 (take εr≈1\varepsilon_r \approx 1). ((a)) Evaluate Λ=ε0ω/σ\Lambda = \varepsilon_0\omega/\sigma and state whether the displacement current may be dropped. ((b)) Calculate the skin depth of the rod at this frequency.

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