The resistivity of gold is 2.44\times 10-8 ?\times m at a temperature of 20°C. Agold wire, 0.5 mm in diameter and 44 cm long, carries a current of380

asked 2021-02-02

The resistivity of gold is \(\displaystyle{2.44}\times{10}-{8}?\times{m}\) at a temperature of \(20^{\circ}C\). Agold wire, 0.5 mm in diameter and 44 cm long, carries a current of 380 ma. The number of electrons per second passing a given crosssection of the wire, is closest to:
a. \(2.4 \times 1018\)
b. \(2.8 \times 1014\)
c. \(1.2 \times 1022\)
d. \(2.4 \times 1017\)
e. \(6.3 \times 1015\)

Answers (1)


Given that resistivuty is ? \(\displaystyle={2.44}\times{10}-{8}?\times{m}\)
\(Length(L) = 0.44m\ radius(R)= (\frac{D}{2}) = 0.25\ mm = 0.25\times 10^{-3}m\)
We know the formula for the resistance is \(\displaystyle{R}=?\frac{{L}}{{A}}={5.47}\times{10}-{2}?\)
Given \(I = 0.380A\)
We know the formula is \(\displaystyle{I}=\frac{{q}}{{t}}=\frac{\ne}{{t}}{n}={I}\frac{{t}}{{e}}={2.4}\times{10}\)

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