What is the predominant form of energy conversion that occurs when electrons strike a target in an x-ray tube?

When electrons strike a target in an x-ray tube, the predominant form of energy conversion is heat. This occurs due to the interaction of high-speed electrons with the target material, which typically consists of a heavy metal such as tungsten. As the electrons collide with the atoms in the target, they impart energy, causing the atoms to vibrate and generate thermal energy, or heat.

While x-rays are indeed produced during this process—specifically through two main interactions called Bremsstrahlung radiation and characteristic radiation—the majority of the energy from the electrons is converted into heat rather than x-rays. In practical terms, about 99% of the energy is converted to heat while around 1% is converted to x-ray photons.

The other forms of energy listed—ultraviolet light and gamma rays—are not produced as a result of the electron interactions in the x-ray tube. Ultraviolet light typically occurs at higher energy levels than visible light but lower than x-rays, and it is not a significant output from an x-ray tube. Gamma rays are produced by radioactive decay and nuclear reactions, which are not relevant to the operation of an x-ray tube. Hence, heat is the accurate answer in the context of energy conversion occurring in an x-ray