A circuit built around a diode (Chapter 12) uses a copper connecting wire of length…

PHYSICS · Subjective · Fermi University Physics · Electricity, Magnetism & Electromagnetism · Condensed Matter, Materials & Soft Matter · Electronic transport in solids

Condensed Matter Physics, Ch Real crystals: vacancies, dislocations and the strength of metals

Problem

A circuit built around a diode (Chapter 12) uses a copper connecting wire of length

L = 2.0\ \mathrm{m}

and cross-sectional area

A = 0.50\ \mathrm{mm^2}

, carrying the diode's forward current of

I = 150\ \mathrm{mA}

. The design allows at most

15\ \mathrm{mV}

of voltage drop across this wire. Recall from Chapter 8 that pure copper at

300\ \mathrm{K}

has resistivity

\rho_e = 1.70\times10^{-8}\ \Omega\,\mathrm{m}

, and recall from this chapter that one atomic per cent of dissolved nickel adds

1.2\times10^{-8}\ \Omega\,\mathrm{m}

at every temperature. Find the maximum nickel content, in atomic per cent, that the wire can carry and still meet the voltage budget.

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