WAEC - Physics (1992 - No. 27)
A real image of an object fom1ed by a converging lens of focal length 15cm is three times the size of the object. What is the distance of the object from the lens?
30cm
25cm
20cm
15cm
10cm
Giải thích
1/u + 1/3u = 1/15; u = 20cm