Question

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

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

Answer 1

Answer: (A)

Wavelength $(\lambda) = 10^{-10}\,m$.
Velocity of the electron, $v = h/m\lambda$
$=\frac{6.6\times10^{-34}}{\left(9.1\times10^{-31}\right)\left(10^{-10}\right)}=7.25\times10^{6}$ m/s.
where $m =$ mass of electron equal to $9.1 × 10^{-31}\, kg$
and $h$ is Planck constant equal to $6.6 × 10^{-34}\, J-s$.