Question

Calculate the velocity of an electron having wavelength of $0.15nm$. Mass of an electron is: $9.109\times {10}^{-28}g$. $(h=6.626\times {10}^{-27}erg-s)$.

• A. $2.062\times {10}^{-8}cm{s}^{-1}$
• B. $2.062\times {10}^{15}cm{s}^{-1}$
• C. $2.062\times {10}^{10}cm{s}^{-1}$
• D. $4.84\times {10}^{8}cm{s}^{-1}$

Answer 1

The correct option is D $4.84\times {10}^{8}cm{s}^{-1}$

Given, $\lambda =0.15\times {10}^{-9}m$
$=0.15\times {10}^{-7}cm$
$h=6.626\times {10}^{-27}erg-s=6.626\times {10}^{-27}{cm}^2-g/sec$
$m=9.109\times {10}^{-28}g$

$\because \lambda =\frac{h}{mv}$

$\therefore 0.15\times {10}^{-7}=\frac{6.626\times {10}^{-27}}{9.109\times {10}^{-28}\times v}$

$v=4.84\times {10}^{8}cm{s}^{-1}$