Question

2. The ratio of the diameter of lenses to its focal length is referred to as..
b) resolution
c) Numerical aperture. d) none of the above.
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Answer 1

Explanation:

A lens with a short focal length and a large angle of view is called a wide-angle lens. ... The maximum usable aperture of a lens is usually specified as the focal ratio or f-number, which is equal to the focal length divided by the effective aperture (or entrance pupil) diameter in the same units.