Question

The kinetic energy of an electron is $4.55\times {10}^{-25}J$. Calculate the de Broglie wavelength for the same.
$h=6.6\times {10}^{-34}Js,\text{mass of electron}=9.1\times {10}^{-31}kg$

• A. $0.72\times {10}^{-5}m$
• B. $0.72\times {10}^{-6}m$
• C. $0.72\times {10}^{-8}m$
• D. $0.72\times {10}^{-7}m$

Answer 1

The correct option is B $0.72\times {10}^{-6}m$

Given:
$\text{Kinetic energy}(K.E.)=4.55\times {10}^{-25}J$
$\text{Mass of electron}\left(m_e\right)=9.1\times {10}^{-31}kgh=6.6\times {10}^{-34}J-sec$

$\text{de Broglie wavelength}\left(\lambda \right)=\frac{h}{\sqrt{2K.E{m}_e}}=\frac{6.6\times {10}^{-34}J-sec}{\sqrt{2\times 4.55\times {10}^{-25}\times 9.1\times {10}^{-31}}}=0.72\times {10}^{-6}m$