Answer:
f = 14.28 m
Explanation:
Given that,
Object distance, u = -50 m
The image distance from the lens, v = +20 m
We need to find the focal length of the lens. Let the focal length is f. Using the lens formula,
[tex]\dfrac{1}{v}-\dfrac{1}{u}=\dfrac{1}{f}[/tex]
Put all the values,
[tex]\dfrac{1}{20}-\dfrac{1}{(-50)}=\dfrac{1}{f}\\\\f=14.28\ m[/tex]
So, the focal length of the lens is equal to 14.28 m.
