Consider a wire of length 4 m and cross-sectional area carrying a current of 2 A. If each cubic meter of the material contains free electrons, find the average time taken by an electron to cross the length of the wire.
Note: Put your answer in hours.
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Use the electron flow equation I = n A v e .
Therefore v = n A e I = 1 0 2 9 × 1 × 1 0 − 6 × 1 . 6 × 1 0 − 1 9 2 = 8 0 0 0 1
And so in order to travel 4 m, it takes 3 2 0 0 0 seconds and therefore 8 . 9 hours.