A potential difference of 2V is applied between the opposite faces of a Ge crystal plate of area 1 cm2 and thickness 0.5 mm. If the concentration of electrons in Ge is $2 × 10^{19}/m^3$ and mobilities of electrons and holes are $0.36\frac{m^2}{volt-sec}$ and $0.14\frac{m^2}{volt-sec}$ respectively, then the current flowing through the plate will be
Answer & explanation
Correct answer: option 4
$σ=ne(μ_e+μ_h)=2× 10^{19}×1.6 ×10^{-19}(0.36+0.14)=1.6(Ω-m^{-1})$
$R=ρ=\frac{I}{A}=\frac{I}{σA}=\frac{0.5×10^{-3}}{1.6×10^{-4}}=\frac{25}{8}Ω$
$∴i=\frac{V}{R}=\frac{2}{25/8}=\frac{16}{25}A=0.64A$