Question

An electron has mass $9.1\times {10}^{-28}g$ and is moving with a velocity of ${10}^{5}cm/sec$. Calculate its wavelength when $h=6.626\times {10}^{-27}erg-sec$.

• A. $\lambda =7.28\times {10}^{-6}cm$
• B. $\lambda =7.28\times {10}^{-5}cm$
• C. $\lambda =3.64\times {10}^{-5}cm$
• D. $\lambda =3.64\times {10}^{-6}cm$

Answer 1

Answer: (B)

$\lambda =7.28\times {10}^{-5}cm$

$\lambda =\frac{h}{mv}$ [De-broglie wavelength]

$\therefore \lambda =\frac{6.626\times {10}^{-27}}{9.1\times {10}^{-28}\times {10}^5}$

$=7.28\times {10}^{-5}cm$

Hence, option $B$ is correct.