Video Transcript
The diagram shows a Coolidge tube used for the production of X-rays. Which of the following is emitted from the component labeled one? (A) X-rays, (B) ions, (C) positrons, (D) electrons, or (E) nothing.
Let’s look at each of these answers individually. The X-rays in a Coolidge tube are not produced at the component that is labeled one, but rather at the component that is labeled two, the anode target. Each individual X-ray that is emitted from the anode target is caused by one of two processes: an energy-level transition or from Bremsstrahlung or breaking radiation. Both of these methods rely on the same thing, though, which is to have electrons impact the anode target at high speeds.
So, component one is certainly not emitting X-rays. Component one, which is a cathode coil, is negatively charged, and component two which is the anode target is positively charged. The larger the difference in the charges, which is to say the higher the potential difference provided here, the higher the energy of the electrons and thus, subsequently, the higher the energy of the X-rays that are produced from the anode target. So, component one, the cathode coil being so negative, ideally, would not have any positrons near it at all.
And though there are charges involved here, ions are not what is emitted from the cathode coil. Since we’re not looking for a generic charged particle, we’re looking for only negatively charged ones, electrons. Electrons are emitted from the component labeled one, the cathode coil, in a process called thermionic emission. So, the correct answer for what is emitted from the component labeled one is (D) electrons.