If the magnification of a virtual image formed of an obje...
If the magnification of a virtual image formed of an object 10cm from a convex lens is 3, then the focal length of the lens is
10cm
15cm
16cm
19cm
20cm
Correct answer is B
V = 3u, U = 10cm
therefore U = -ve,
F = UVU+V
= 10×(−30)10−30
= 15cm