A wire carries a steady current of 3.2 mA. Take e = 1.6 × 10⁻¹⁹ C. How many electrons pass a given cross-section of the wire each second?
Correct answer A. 2.0 × 10¹⁶
Explanation
Number per second n = I/e = 3.2 × 10⁻³ A ÷ 1.6 × 10⁻¹⁹ C = 2.0 × 10¹⁶ electrons per second. Forgetting the milli prefix gives 2.0 × 10¹⁹.
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