Question

A current of 10 A exists in a wire of cross-sectional area of \( 5 \times 10^{-6} \, \text{m}^2 \) with a drift velocity of \( 2 \times 10^{-3} \, \text{m/s} \). The number of free electrons in each cubic meter of the wire is:

• A. \( 2 \times 10^{25} \)
• B. \( 2 \times 10^{23} \)
• C. \( 625 \times 10^{25} \)
• D. \( 2 \times 10^{6} \)

Hint:

Drift velocity is extremely small, and the number of free electrons in a conductor is very large. Use the equation \( I = n A e v_d \) to determine electron density.