Question

The energy of a characteristic photon from a Coolidge tube comes from:

• A. The kinetic energy of the striking electron
• B. The kinetic energy of the free electrons of the target
• C. The kinetic energy of the ions of the target
• D. An atomic transition in the target.

Answer 1

The correct option is D An atomic transition in the target.

Characteristic x-rays is a unique property of individual elements.
A high energy electron knocks out an already existing electron in one of the shells of an anode atom, thus creating a vacancy in that particular shell of the atom.
This event energizes the atom and an electron from a higher shell jumps to fill the vacancy in the lower shell so that the overall energy of the atom is decreased. This decrease in energy gives birth to the x-ray photon.
So, characteristic x-ray photons are consequences of energy level transitions in the anode atoms.