Question

A camera lens used for taking close-up photographs has a focal length of 23.0 mm. The farthest it can be placed from the film is 34.0 mm. (a) What is the closest object (in mm) that can be photographed

Answer 1

Answer:

The object distance is 71.09 mm.                              

Explanation:

A camera lens used for taking close-up photographs has a focal length of 23.0 mm, f = 23 mm

The farthest it can be placed from the film is 34.0 mm, v = -34 cm

Using lens formula as follow :

$\dfrac{1}{u}-\dfrac{1}{v}=\dfrac{1}{f}$

$\dfrac{1}{u}=\dfrac{1}{f}+\dfrac{1}{v}\\\\\dfrac{1}{u}=\dfrac{1}{23}+\dfrac{1}{(-34)}\\\\u=71.09\ mm$

So, object distance is 71.09 mm.