Question

An electron falls from rest through a potential difference of 100v. What is its de broglie wavelength.[me=9.1x10-31kg]

Answer 1

mass of electron, m = 9.1 × 10^-31 kg

charge on electron, q = 1.6 × 10^-19 C

potential difference through electron , V = 100 volts

from De-broglie's wavelength equation,

$\lambda=\frac{h}{\sqrt{2qVm}}$

here h is plank's constant. and value of h = 6.63 × 10^-34 Js

so, $\lambda$ = 6.63 × 10^-34/√{2 × 1.6 × 10^-19 × 100 × 9.1 × 10^-31}

= 6.63 × 10^-34/√{29.12 × 10^-48}

= 6.63 × 10^-34 /5.4 × 10^-24

= 1.227 × 10^-10 m

= 1.227 A°

hence, De-broglie's wavelength = 1.227 A°