A photographic camera with a lens of focal length 5 cm is used for capturing images. The vertical length of the film used is 24 mm in which image of a 1.68 m tall man is to be captured. Find the minimum distance (in m) of the man from the lens such that his complete image can be obtained.

Answer

`03.55`

Explanation

The lens of the camera is convex and the image is inverted
`m=(h_(i))/(h_(0))=-(24mm)/(1.68m)=-1/70`
`m=f/(f+u)=-1/70`
`70f=-f-u`
`-u=71f=355cm=3.55m`