For many years, the Palomar telescope (5-m diameter) in California was the largest telescope in the world; it has now been surpassed by a number of facilities, including both the Keck I and Keck II telescopes (each of diameter 10 m) in Hawaii. How much greater is the light-gathering power of a Keck telescope than that of the Palomar telescope?
A) 4 times greater
B) 8 times greater
C) 2 times greater
D) 1.4 times greater

Question

Quizplus · Accepted Answer

The light-gathering power of a telescope is proportional to the area of its aperture, which is proportional to the square of its diameter. The Keck telescope has a diameter of 10 m, and the Palomar telescope has a diameter of 5 m. The ratio of their light-gathering powers is (10/5)^2 = 4.

For Many Years, the Palomar Telescope (5-M Diameter) in California