At room temperature, copper has free electron density of 8.4 x 10^28 m-3. The electron drift velocity in a copper conductor of cross-sectional area 10-6 m2 and carrying a current of 5.4 A, will be:
Correct answer: D. 0.4 mms-1
- A. 4 ms-1
- B. 0.4 ms-1
- C. 4 cms-1
- D. 0.4 mms-1
Explanation
To determine the drift velocity (vd), use the formula vd = i/(neA), where i is the current, n is the free electron density, e is the elementary charge, and A is the cross-sectional area. Given that the current i is 5.4 A, the electron density n is 8.4 × 1028 m-3, and the area A is 10-6 m2, the drift velocity calculates to approximately 0.4 mm/s. Options A, B, and C are incorrect because they either miscalculate the drift velocity or misinterpret the units, resulting in values that do not match the expected range of millimeters per second.
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