A camera is used to photograph the full moon,which has an angular diameter of 0.53°.The image on the film is 2.3 mm in diameter.What is the focal length of the lens?
A)2.3 mm
B)500 mm
C)250 mm
D)790 mm
E)25.5 mm

Question

A camera is used to photograph the full moon,which has an angular diameter of 0.53°.The image on the film is 2.3 mm in diameter.What is the focal length of the lens?
A)2.3 mm
B)500 mm
C)250 mm
D)790 mm
E)​25.5 mm

Quizplus · Accepted Answer

The focal length (f) can be calculated using the formula: f = (image diameter / angular diameter in radians). First, convert the angular diameter from degrees to radians: 0.53° * (π/180) = 0.00925 radians. Then, f = 2.3 mm / 0.00925 = 248.65 mm, which is approximately 250 mm.

A Camera Is Used to Photograph the Full Moon,which Has