Lens — Image of Virtual ObjectHardQuestion 20236
Question
A converging beam appears to converge at a point 30 cm behind a concave lens (f = −20 cm). The actual image is at:
- A12 cm behind the lens
- B60 cm behind the lens
- C60 cm in front of the lensCorrect
- DAt infinity
Correct answer
60 cm in front of the lens
Explanation
Virtual object at u = +30 cm (behind the lens). 1/v = 1/f + 1/u = 1/(−20) + 1/30 = −3/60 + 2/60 = −1/60 → v = −60 cm. The negative image distance places the real image 60 cm in front of the lens.