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