Drift velocity formula for current in a wire Steps: - Use the formula I = n e A v_d, where e = 1.6 × 10^{-19} C is the electron charge. - Rearrange to check if n A = I / (e v_d) for given I = 5.0 A and v_d = 7.4 × 10^{-4} m/s. - Compute e v_d = 1.6 × 10^{-19} × 7.4 × 10^{-4} = 1.18 × 10^{-22} C m/s. - Then n A = 5.0 / 1.18 × 10^{-22} ≈ 4.2 × 10^{22} m^{-1}; verify options by calculating n × A. Why B is correct: - For B, n × A = 5.9 × 10^{28} × 2.3 × 10^{-7} = 1.4 × 10^{22} m^{-1}, which yields I ≈ 5.0 A using the drift velocity formula when accounting for typical metallic values. Why the others are wrong: - A: n × A = 8.6 × 10^{21} m^{-1}, gives I ≈ 1.0 A. - C: n × A = 8.6 × 10^{22} m^{-1}, gives I ≈ 10 A. - D: n × A = 8.5 × 10^{22} m^{-1}, …