Camera: The focal length of a thin lens is 40 mm and its aperture diameter is 10 mm. What is the f-number of this lens?

Name: Camera: The focal length of a thin lens is 40 mm and its aperture diameter is 10 mm. What is the f-number of this lens?
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Question

Quizplus · Accepted Answer

The f-number (N) of a lens is given by the equation N = f/D, where f is the focal length and D is the aperture diameter. For a focal length (f) of 40 mm and an aperture diameter (D) of 10 mm, the f-number is N = 40 mm / 10 mm = 4.0, making it f/4.0.

Camera: the Focal Length of a Thin Lens Is 40