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 $\lambda_{\text {electron }}=\frac{h}{m_{e} v}$
$\Rightarrow v=\frac{h}{m_{e} \lambda_{e}}$
$=\frac{6.6 \times 10^{-34}}{9.1 \times 10^{-31} \times 10^{-10}}$
$=7.25 \times 10^{6}\, m / s$