A block of pure silicon at 300 K has a length 0 . t m and area of $1\cdot 0\times {10}^{-4}{\mathrm{m}}^2$ if a battery of emf z y is connected across it, what is the electron current ? The mobility of electrons is $0\cdot 14m^2{V}^{-1}{s}^{-1}$  and their number density is $1\cdot 5\times {10}^{16}{\mathrm{m}}^{-3}$

• A

  $6\cdot 72\times {10}^{-7}\mathrm{A}$

• B

  $6\cdot 72\times {10}^{-8}\mathrm{A}$

• C

  $6\cdot 72\times {10}^{-9}\mathrm{A}$

• D

  $6\cdot 72\times {10}^{-10}\mathrm{A}$