For thin lens, when image distance equals object distance (|v| = |u|), object position is:
- At 2f (object and image both at 2f)
- At f
- Half of f
- At infinity
Show answer and solution
Correct answer: A. At 2f (object and image both at 2f)
For convex lens, |v| = |u| occurs at u = 2f.
Then v = 2f, m = -1 (same size, inverted, real).
Useful for image relay systems.