X-rays are produced when a fast-moving stream of electrons hits which type of target?

X-rays are produced when a fast-moving stream of electrons collides with a target material that has a high atomic number and a high melting point. Tungsten is the preferred target material in X-ray tubes for several reasons. It has an atomic number of 74, which allows for effective X-ray production due to its ability to emit high-energy photons when struck by electrons.

The high melting point of tungsten (approximately 3,422 degrees Celsius) is crucial because during the X-ray generation process, substantial heat is produced. Tungsten can withstand these extreme temperatures without damaging the X-ray tube, ensuring durability and effectiveness over time.

In contrast, while materials like copper, aluminum, and silver may have some properties useful in electronics or other applications, they do not provide the same level of efficiency in producing X-rays when hit by high-speed electrons. Therefore, tungsten is the optimal choice for X-ray production due to its combination of high atomic number and thermal resilience.