Answer
the concentration of electron/ volume (n) = 8.5 × 10²⁸ /m³
the drift velocity of electron
[tex]v = \dfrac{I}{neA}[/tex]
[tex]v = \dfrac{143}{8.5\times 10^{28}\times 1.6\times 10^{-19}\times 40.2 \times 10^{-6}}[/tex]
v = 2.615 × 10⁻⁴ m/s
time require is
[tex]t=\dfrac{L}{v}[/tex]
[tex]t=\dfrac{0.845}{2.615\times 10^{-4}}[/tex]
t = 3231.35 s
