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A potential difference of 2 \mathrm{~V} is applied between the opposite faces of a Ge crystal plate of area 1 \mathrm{~cm}^2 and thickness0.5 \mathrm{~mm}. If the concentration of electrons in G eis  2 \times 10^{19} / \mathrm{m}^3 and mobilities of electrons and holes are0.36 \frac{\mathrm{m}^2}{\text { volt-s }}\, \, and\,\, 0.14 \frac{\mathrm{m}^2}{\text { volt-s }} respectively, then the current flowing through the plate will be

Option: 1

0.25 A


Option: 2

0.45 A


Option: 3

0.56 A


Option: 4

0.64 A


Answers (1)

best_answer

\mathrm{\begin{aligned} & \sigma=n e\left(\mu_e+\mu_h\right)=2 \times 10^{19} \times 1.6 \times 10^{-19}(0.36+0.14) \\ & =1.6(\Omega-m)^{-1} \\ & R=\rho \frac{l}{A}=\frac{l}{\sigma A}=\frac{0.5 \times 10^{-3}}{1.6 \times 10^{-4}}=\frac{25}{8} \Omega \\ & \therefore i=\frac{V}{R}=\frac{2}{25 / 8}=\frac{16}{25} \mathrm{~A}=0.64 \mathrm{~A} \end{aligned} }

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Irshad Anwar

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