Final answer:
The size ratio between the input and output phosphor screens is known as output gain, crucial in image systems like CRTs and affects image brightness and quality.
Step-by-step explanation:
The term that refers to the size ratio between the input and output phosphor screens is known as output gain. In radiology and imaging physics, this ratio is significant as it affects the image quality and the efficiency of the imaging system. Typically, output gain quantifies the degree by which image brightness is increased, which is essential in producing diagnostic images. The determination of output gain is rooted in understanding the relationship between the input phosphor size and output phosphor size, as well as their implications on image resolution and brightness.
For instance, in the context of a Cathode Ray Tube (CRT), the accelerating potential used would affect the frequency of the photon produced. Meanwhile, in optical experiments such as photon emission or double slit experiments, understanding the phosphors and their interaction with light play a crucial role in interpreting the results and the functioning of the devices.