As an electron impacts the target inside a Coolidge tube, its total...

When high-speed electrons strike the target in a Coolidge tube, they interact with the atoms of the target material.

An electron may lose its entire kinetic energy in a single collision, resulting in the emission of an X-ray photon of maximum energy. In this case, the total kinetic energy is converted into a photon.

Alternatively, the electron may undergo multiple collisions, losing its kinetic energy gradually. This energy increases the thermal agitation of the target atoms, meaning the kinetic energy is converted into heat.

Therefore, the total kinetic energy of the electron may be converted into a photon or may be converted into heat.