How much more light will be collected by the optics of one side of a pair of binoculars (7 × 50,with magnification of 7 and an objective lens aperture diameter of 50 mm)compared to that collected by an average human eye with a typical aperture diameter of 5 mm?
A) 10
B) 2500
C) 100
D) 1.4,or 7/5

Question

Quizplus · Accepted Answer

The light-gathering power of an optical instrument is proportional to the area of its aperture. The area is proportional to the square of the diameter, so the ratio of the light collected by the binoculars to that collected by the eye is (50/5)^2 = 100.

How Much More Light Will Be Collected by the Optics