Question

The mean free path of electrons in a metal is $4 \times 10^{-8}m.$ The electric field which can give on an average $2\, eV$ energy to an electron in the metal will be in units $V/m$

• A. $5 \times 10^{-11}$
• B. $8 \times 10^{-11}$
• C. $5 \times 10^7$
• D. $8 \times 10^7$

Answer 1

Answer: (C)

Energy $=2 eV =e E \lambda$
$\therefore E=\frac{2 e V}{e \lambda}=\frac{2}{4 \times 10^{-8}}=5 \times 10^{7} V / m$