What is the light-gathering power of an 8-inch telescope compared to a 4-inch telescope?
A)2 times better
B)4 times better
C)8 times better
D)16 times better
E)32 times better

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. An 8-inch telescope has a diameter twice that of a 4-inch telescope, so its light-gathering power is 2^2 = 4 times better.

What Is the Light-Gathering Power of an 8-Inch Telescope Compared