At room temperature, copper has free electron density of 8.4 x 10²⁸ 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
The drift velocity (vd) is given by the formula I = n A vd e, where I is current, n is electron density, A is area, and e is electron charge. Rearranging gives vd = I / (nAe). Plugging in the values yields a velocity of 0.0004 m/s, which is 0.4 mm/s.
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