Question

Find the wavelength associated with an electron which has mass $9.1\times {10}^{-28}g$ and is moving with a velocity of ${10}^{5}cm$ ${sec}^{-1}$. (Given: $h=6.625\times {10}^{-27}erg-sec$).

• A. $\lambda =5.28\times {10}^{-5}m$.
• B. $\lambda =7.28\times {10}^{-5}cm$.
• C. $\lambda =7.28\times {10}^{-5}m$.
• D. $\lambda =5.28\times {10}^{-5}cm$.

Answer 1

The correct option is B $\lambda =7.28\times {10}^{-5}cm$.

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

$\therefore \lambda =\frac{6.625\times {10}^{-27}}{9.1\times {10}^{-28}\times {10}^5}=7.28\times {10}^{-5}cm$

$Note:$ Units should be taken care of .