Final answer:
The f-number of the lens is 5.0 . The f-number of a lens with a 35mm focal length and a 7.0mm diameter aperture is f/5.
Step-by-step explanation:
The f-number of a lens can be calculated by dividing the focal length of the lens by the diameter of the aperture. In this case, the focal length is given as 35mm and the aperture diameter is given as 7.0mm. So, the f-number can be calculated as:
f-number = focal length / aperture diameter = 35mm / 7.0mm = 5.0
Therefore, the f-number of the lens is 5.0.