What is the focal length of a convex lens of focal length in contact with a concave lens of focal length ? Is the system a converging or a diverging lens? Ignore the thickness of the lenses.
Step 1: Given information
The focal length of the convex lens is .
The focal length of the concave lens is
Step 2: To find
The focal length of a convex lens
Step 3: Finding the focal length
We know the formula,
By substituting the values,
Hence, the combined focal length of the lenses is and, the negative sign implies that its lens system is a diverging lens.