- #1

Von Neumann

- 101

- 4

Determine the wavelength and frequency of the emitted x-rays when 100-keV electrons strike a target.

Solution:

Assuming all kinetic energy of electrons is used to produce the x-rays,

E_initial=E_final

K+m_0*c^2=hf+m_0*c^2

K=hf

K=hc/λ

=>λ=hc/K=(6.63x10^-34 Js)(3.00x10^8 m/s)/(1.60x10^-14 J) [because 100 keV =1.60x10^-14 J]

λ=0.12 Å

Also since K=hf,

f=K/h=(1.60x10^-14 J)/(6.63x10^-34 Js)=2.4x10^-19 Hz

Is this correct?