American Registry of Radiologic Technologists (ARRT) Practice Exam

As the potential difference increases, what is produced in greater amounts?

1. Long wavelengths

2. Short wavelengths

3. Medium wavelengths

4. No wavelengths

The correct answer is: Short wavelengths

As the potential difference increases in an x-ray tube, the kinetic energy of the electrons that are accelerated towards the anode also increases. This higher kinetic energy results in photons that have greater energy levels. According to the principles of electromagnetic radiation, higher energy photons correspond to shorter wavelengths. In the context of x-ray production, as the potential difference rises, more high-energy x-rays are produced, which are associated with shorter wavelengths. This understanding is fundamental in radiology because the quality and penetrative ability of x-rays can be manipulated by adjusting the potential difference, impacting the exposure and diagnostic value of the imaging. Longer wavelengths, on the other hand, correspond to lower energy photons, which would be produced under lower potential differences. Thus, an increase in potential difference does not create long wavelengths or medium wavelengths, nor does it halt the production of wavelengths entirely. Instead, it specifically favors the production of shorter wavelengths due to the relationships between energy, frequency, and wavelength encapsulated in the equation \(E = \frac{hc}{\lambda}\), where \(E\) is energy, \(h\) is Planck’s constant, \(c\) is the speed of light, and \(\lambda\) is wavelength.