All Problems

Electric Current

Problem 3.208

A copper wire carries a current of density j=1.0 A/mm2j=1.0 \mathrm{~A} / \mathrm{mm}^{2} Assuming that one free electron corresponds to each copper atom, evaluate the distance which will be covered by an electron during its displacement l=10 mml=10 \mathrm{~mm} along the wire.

Reveal Answer
s=enl⟨v⟩/j∼107 m, where n is the concentration of free electrons, (v) is the mean velocity of thermal motion of an electrons=e n l\langle v\rangle / j \sim 10^{7} \mathrm{~m}, \text { where } n \text { is the concentration of free electrons, (v) is the mean velocity of thermal motion of an electron}
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