Which factor decreases edge sharpness and increases magnification in radiographs?

The factor that decreases edge sharpness and increases magnification in radiographs is a far object-image receptor distance. When the object is positioned farther away from the image receptor, the parallel rays of radiation that produce the image diverge more, which can lead to a larger area of blurriness at the edges of the image. This decreased edge sharpness is due to the increased distance that the x-ray photons travel before hitting the receptor, causing a loss in the fidelity of the image's outlines.

Additionally, increasing this distance between the object and the image receptor leads to greater magnification of the object as it appears on the radiograph. The geometric principles governing radiography dictate that as the object distance increases, the magnification factor also rises, making the object appear larger than its actual size. This is a fundamental concept in radiographic imaging related to how distance affects image quality and clarity.

In contrast, options such as a close object-image receptor distance, an increase in exposure time, and the use of high-speed film are associated with improved sharpness and reduced magnification due to less divergence of the x-ray beam, shorter exposure conditions, and finer resolution capabilities, respectively.