The secondary mirror of a telescope whose primary mirror is 4 m in diameter has a diameter of 0.5 m.What percentage of the incoming light is obstructed by this secondary mirror?
A) about 1.6%
B) about 12.5%, or 1/8
C) about 35%
D) about 16%

Question

Quizplus · Accepted Answer

The area of the secondary mirror is (0.5 m)^2 = 0.25 m^2. The area of the primary mirror is (4 m)^2 = 16 m^2. Therefore, the percentage of the incoming light that is obstructed by the secondary mirror is (0.25 m^2 / 16 m^2) * 100% = 1.56%.

The Secondary Mirror of a Telescope Whose Primary Mirror Is