Answer:
f = 17.14 cm
Explanation:
Given that,
The object distance, u = -40 cm
The image distance, v = +30 cm
We need to find the focal length of the lens. The lens formula is given by :
[tex]\dfrac{1}{v}-\dfrac{1}{u}=\dfrac{1}{f}\\\\\dfrac{1}{f}=\dfrac{1}{30}-\dfrac{1}{(-40)}\\\\f=17.14\ cm[/tex]
So, the focal length of the lens is 17.14 cm.
