Final answer:
The X-ray film holding device is considered to be a radiography instrument in physics. X-ray film is a common detector of ionizing radiation, used in medical and dental X-rays.
Step-by-step explanation:
The X-ray film holding device is considered to be a radiography instrument in physics. X-ray film is the most common detector of ionizing radiation, used in medical and dental X-rays. The film is exposed to radiation, which interacts with the emulsion and alters it chemically, resulting in a darkening of the film. This darkening is related to the type and amount of radiation exposure.