ASNT Industrial Radiography Radiation Safety Practice Test

How are X-rays produced in an X-ray tube?

1. Through the compression of air within the tube

2. By the passage of electrons across the tube striking the target

3. By heating the target material to extreme temperatures

4. Through the use of magnetic fields

The correct answer is: By the passage of electrons across the tube striking the target

X-rays are produced in an X-ray tube through the interaction of high-speed electrons with a target material, usually made of tungsten. When electrons are emitted from the cathode, they are accelerated toward the anode (the target) by an electric field. Upon striking the anode, these electrons collide with the atoms of the target material, resulting in two primary processes: characteristic radiation and Bremsstrahlung (or "braking radiation"). Characteristic radiation occurs when electrons dislodge inner-shell electrons from the target material's atoms, causing energy transitions between electron shells that emit X-rays. Bremsstrahlung radiation is produced when the high-speed electrons are decelerated by the electric fields of the nuclei in the target material, releasing energy in the form of X-rays. This process showcases the fundamental principle of X-ray generation through electron interaction rather than the other choices, which do not accurately describe how X-ray production occurs. For example, compressing air would not create X-rays, nor would simply heating the target material. Additionally, magnetic fields do not play a role in the direct production of X-rays in this context. Understanding this interaction is crucial for those working with X-ray equipment and safety protocols in industrial radiography.