Question

The speed of an electron having a wavelength of $10^{-10}m$ is

• A. $7.25\times 10^{6}m/s$
• B. $6.26\times 10^{6}m/s$
• C. $5.25\times 10^{6}m/s$
• D. $4.24\times 10^{6}m/s$

Answer 1

Answer: (A)

By using ${\lambda }_{\text{electron }}=\frac{h}{m_{e}v}$
$\Rightarrow v=\frac{h}{m_e{\lambda }_e}$
$=\frac{6.6\times 10^{-34}}{9.1\times 10^{-31}\times 10^{-10}}$
$=7.25\times 10^{6}m/s$