Question

Two equiconvex lenses of focal lengths 30 cm and 70 cm, made of material of refractive index = 1.5, are held in contact coaxially by a rubber band round their edges. A liquid of refractive index 1.3 is introduced in the space between the lenses filling it completely. Find the position of the image of a luminous point object placed on the axis of the combination lens at a distance of 90 cm from it.

Answer 1

This system is combination of three lenses. Two lenses of glass one lens of liquid. Add the powers to get total power.

Hence, both the images are real and inverted, the first is magnification −0.25, and the second is −4.00.