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

The correct option is A $7.25\times {10}^{6}m/s$

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