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Question
Electron drift speed is estimated to be of the order of mm s−1. Yet large current of the order of few amperes can be set up in the wire. Explain briefly.
Solution
Electron drift is estimated to be of the order of mm s−1. However, the current set up in the wires is of the order of few amperes. This is because the electron density is very large in a material. It is of the order 1028/m3 of the wire. Hence, all these electrons contribute to the total current. Therefore, despite having small drift speeds, the current set up in wires is large.
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