Question

The de-Broglie wavelength of an electron of speed $0.5\, km\, s ^{-1}$ is

• A. $1.5 \times 10^{-6} m$
• B. $1.5 \times 10^{-8} m$
• C. $1.5 \times 10^{-10} m$
• D. $1.5 \times 10^{-12} m$

Answer 1

Answer: (A)

$ \lambda=\frac{h}{p}=\frac{h}{m v}$
$\Rightarrow \lambda=\frac{6.6 \times 10^{-34} J s }{\left(9.1 \times 10^{-31} kg \times 500 ms ^{-1}\right)}=1.5 \times 10^{-6} m$