Solve the problem.
-A reflecting telescope contains a mirror shaped like a paraboloid of revolution. If the mirror is 24 inches across at its opening and is 4 feet deep, where will the light be concentrated?
A) 0.1 in. from the vertex
B) 10.1 in. from the vertex
C) 0.2 in. from the vertex
D) 0.8 in. from the vertex

Question

Quizplus · Accepted Answer

The formula for the focal length (f) of a paraboloid is f = d^2 / (16c), where d is the diameter and c is the depth. Here, d = 24 inches and c = 48 inches (4 feet). Plugging in these values gives f = 24^2 / (16*48) = 0.8 inches.

Solve the Problem. -A Reflecting Telescope Contains a Mirror Shaped Like a Paraboloid