Suppose we somehow knock out an electron from an atom. The energy level of the e

Question

Suppose we somehow knock out an electron from an atom. The energy level of the electron is -13.4 keV. Another electron in that atom makes a transition from its level at 1.8 keV to that empty level and emits a photon. (a) Find the energy (keV) of the emitted photon. (b) Find the wavelength (nm) of the photon. This is how x rays are produced in commercial instruments. A beam of high-energy electrons are directed at a target where they knock electrons out of atoms. Other electrons in the atoms make transitions to these empty levels, emitting photons.

Explanation / Answer

Energy lost by a photon = -1.8 keV - 13.4 KeV) = -15.2 keV

part B :

now use

we know that a photon of energy is E = hf = hc/L

E is energy in joules

f being frequency

h being 6.626*10^-34

c being speed of light 3.0*10^8

so

wavelength L = 6.626 e -34 * 3e8/(15.2 *1000* 1.6 e -19)

L = 81.73 pm or 0.81 Armstng units
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