Question

The energy of a photon of characteristic X-ray from a Cooling tube comes from.

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

Answer 1

The correct option is A The kinetic energy of the free electrons of the target

In the Coolidge tube the electrons are produced by thermionic effect from a tungsten filament heated by an electric current.The filament is the cathode of the tube.the high voltage potential is between the cathode and anode,the electrons are thus accelerated and then hit the anode.The kinetic enrgy of the free electrons of the target is the source of energy of photon of characteristic $X$-ray from a cooling tube.