Question

What must be the velocity of a beam of electrons if they are to display a deBroglie wavelength of 1Astrom

Answer 1

answer : 7.28 × 10^6 m/s

explanation : De- Broglie's wavelength of beam of electrons , $\lambda$ = 1 Å = 10^-10 m

we have to find velocity of beam of electrons .

use De - Broglie's equation,

$\lambda=\frac{h}{mv}$

or, $v=\frac{h}{m\lambda}$

here, h is plank's constant e.g., h = 6.626 × 10^-34 Js, m is mass of electron.e.g., m = 9.1 × 10^-31 Kg

v = 6.626 × 10^-34/(10^-10 × 9.1 × 10^-31)

= (6.626/9.1) × 10^{-34 + 10 + 31}

= 0.728 × 10^7 m/s

= 7.28 × 10^6 m/s