Question

For a copper block, find the electric field which can give on an average $ 1 \,eV $ energy to a conduction electron. (The mean free path of conduction electrons in copper is given as $ 4 \times 10^{-8}\, m $ )

• A. $ 2.62 \times 10^{7}\,V\,m^{-1} $
• B. $ 2.64 \times 10^{7}\,V\,m^{-1} $
• C. $ 2.5 \times 10^{7}\,V\,m^{-1} $
• D. $ 2.58 \times 10^{7}\,V\,m^{-1} $

Answer 1

Answer: (C)

Energy transfer to conduction electron
$U=eV=e\times E \times d $
$[\because V=E \times d]$
$E=\frac{U}{e\times d} $
$=\frac{1\,eV}{e\times4\times10^{-8}}$
$=\frac{1.6\times10^{-19}J}{1.6\times10^{-19}\times4\times10^{-8}}$
$=2.5\times10^{7}V\,m^{-1}$