Question

The de-Broglie wavelength associated with an electron moving with a speed of $5.4\times 10^{6}m{s}^{-1}$ is

• A. $0.135nm$
• B. $0.125nm$
• C. $0.150nm$
• D. $0.145nm$

Answer 1

Answer: (A)

For the electron,
Mass, $m=9.11\times 10^{-31}kg$, speed
$v=5.4\times 10^{-6}m{s}^{-1}$
Then, momentum
$p=mv=9.11\times 10^{-31}\times 5.4\times 10^6$
$=4.92\times 10^{-24}kgm{s}^{-1}$
de-Broglie wavelength, $\lambda =\frac{h}{p}$
$=\frac{6.63\times 10^{-34}Js}{4.92\times 10^{-24}kgm{s}^{-1}}$
$=0.135nm$