The focal length of the lens is 5 cm.
The solution to the problem:
Given:
Distance of the image formed by the lens from its second focus (x2) = 30 cm
Distance of the object from the first focus (x1) = 10 cm
We need to find:
Focal length of the lens (f)
Formula:
For a thin lens, the following formula relates the object distance (x1), image distance (x2), and focal length (f):
1/f = 1/x1 + 1/x2
Solving for focal length:
Plugging in the given values, we get:
1/f = 1/10 + 1/30
Simplifying the equation, we get:
1/f = 0.2
Solving for f, we get:
f = 5 cm
Therefore, the focal length of the lens is 5 cm.