Question 28
Lenses and Optical InstrumentsA lens of focal length 12.0 cm forms an upright image three times the size of a real object. The distance between the object and the image is
- A.8.0 cm
- B.16.0 cm
- C.24.0 cm
- D.32.0 cm
Show the answer and explanation
Answer: B (16.0 cm)
Explanation
An upright, magnified image from a converging lens is virtual and on the same side as the object, with v = −3u. 1/u − 1/(3u) = 1/12 gives u = 8 cm and the image 24 cm from the lens, so they are 24 − 8 = 16 cm apart.