The pupil of the human eye is approximately 0.8 centimetres in diameter when adapted to the dark.What is the ratio of the light-gathering power of a 1.6 metre telescope to that of the human eye?
A)2 : 1
B)20 : 1
C)400 : 1
D)40,000 : 1

Question

Quizplus · Accepted Answer

The light-gathering power of a telescope is proportional to the area of its aperture. The area is proportional to the square of the diameter. The telescope's diameter is 1.6 meters (160 cm), and the eye's diameter is 0.8 cm. The ratio of their areas is (160/0.8)^2 = 40,000.

The Pupil of the Human Eye Is Approximately 0