Question

Calculate the wavelength associated with an electron moving with a velocity of ${10}^{10}cm/s.$

• A. $0.072\stackrel{\circ }{A}$
• B. $0.829\stackrel{\circ }{A}$
• C. $0.667\stackrel{\circ }{A}$
• D. $1.009\stackrel{\circ }{A}$

Answer 1

The correct option is A $0.072\stackrel{\circ }{A}$

Given :
$\text{Planck's constant}\left(h\right)=6.63\times {10}^{-27}ergs\text{Velocity of electron}\left(v\right)={10}^{10}cm/s$
We know that:
$\text{Mass of electron}\left(m_e\right)=9.1\times {10}^{-28}g$
$\text{de Broglie wavelength}\left(\lambda \right)=\frac{h}{mv}=\frac{6.63\times {10}^{-27}}{9.1\times {10}^{-28}\times {10}^{10}}=7.28\times {10}^{-10}cm=0.072\stackrel{\circ }{A}$