A wire carries a current of 2.0 A. What is the charge that has flowed through its cross-section in 1.0 s. How many electrons does this correspond to?
Correct answer: B. 2.0 C, 1.25 x 10^19
- A. 3.0 C, 1.25 x 10^19
- B. 2.0 C, 1.25 x 10^19
- C. 4.0 C, 1.25 x 10^19
- D. 2.0 C, 5.25 x 10^19
Explanation
The current flowing through a wire is defined as the charge passing through a cross-section of the wire per unit time, given by the formula i = q/t. In this problem, we have i = 2.0 A and t = 1.0 s, so the charge q = it = (2.0 A)(1.0 s) = 2.0 C. To find the number of electrons, we use the formula q = ne, where e is the charge of one electron (approximately 1.6 × 10-19 C). Rearranging for n, we get n = q/e = 2.0 C / 1.6 × 10-19 C = 1.25 × 1019 electrons. Therefore, the correct option is B. Option A is incorrect due to the incorrect charge value, Option C is incorrect due to both incorrect charge and electron count, and Option D is incorrect due to an incorrect electron count.
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