Final answer:
The practical limit mentioned in the question refers to the maximum size of the light-collecting unit in a telescope.
Step-by-step explanation:
The subject of this question is Physics and the grade is High School.
The practical limit mentioned in the question refers to the maximum size of the light-collecting unit in a telescope.
There are practical limits to the size of a telescope's light-collecting unit because of various factors such as the weight and support of the lens, diffraction, and the need for precise manufacturing of the lens sides for a sharp image.