A lens is made up of 3 different transparent media as shown in figure. A point object O is placed on its axis beyond 2f. How many real images will be obtained on the other side?

Focal length of a lens is given by,
$\frac{1}{f}=(\mu -1)\left(\frac{1}{R_1}-\frac{1}{R_2}\right)$, when it is kept in air.
Where μ is the refractive index of the lens medium, and R₁ and R₂ are radii of curvature of the curved surfaces.
Here, lens has three different materials, so it will have three focal lengths. As, object is outside ‘2f’, three diminished, real image will form.