A convex lens is made of 3 layers of glass of 3 different materials as in the figure. A point object is placed on its axis. The number of images of the object are

Options

A. 3
B. 4
C. 1
D. 2

Answer

C

Explanation

`(1)/(f)=(mu-1)((1)/(R_(1))(1)/(R_(2)))`.
For the first lens `R_(1)=R_(2)`.
`R_(1)andR_(2)` are positive , Therefore the first lens and similary the lens are ineffective . The middle one alone is the lens that gives the image . Therefore one image will be got .