Video Transcript
Which of the following could be a source of X-ray radiation? (A) Alternating electric currents. (B) Thermal motion of atoms and molecules. (C) High-speed electrons impacting on a metal plate. (D) Decaying atomic nuclei. (E) None of the answers is correct.
Among our answer options, we have four different physical processes. We want to know which one, if any, could be a source of X-ray radiation. Let’s begin by recalling the electromagnetic spectrum. This spectrum describes electromagnetic radiation of all frequencies. It is typically divided up into seven larger sections. Moving from the higher-energy end of the spectrum towards the lower-energy end, we have 𝛾 rays, then X-rays, then ultraviolet radiation, then visible radiation, then infrared radiation, then microwaves, and finally radio waves.
If we move through our answer possibilities, starting with option (A), we can note that alternating electric currents are used to generate microwaves as well as radio waves. They’re not, however, used as a source of X-ray radiation. Next, option (B) names thermal motion of atoms and molecules. The radiation given off by these processes though is typically infrared radiation, or IR for short. We won’t choose this process as a source of X-rays either.
Option (C) describes high-speed electrons impacting on a metal plate. This process, which is used in a device called a Coolidge tube, is indeed a source of X-ray radiation. It looks then that answer option (C) will be our final answer. But just to make sure, let’s consider option (D) as well. When atomic nuclei decay, the energy associated with these decays is high enough that the radiation produced is classified as 𝛾 rays. These are different to X-rays, so we won’t choose answer option (D). And since option (C) is a correct source of X-ray radiation, we also won’t choose answer choice (E).
Our final answer then is option (C). High-speed electrons impacting on a metal plate could be a source of X-ray radiation.
