Explanation

The human eye operates like a convex lens imaging system. The size of the image formed on the retina is directly proportional to the magnification, which depends on the object height, object distance, and image distance from the lens.

Using the relation:

Magnification=hiho=−vuMagnification=hohi=−uv

• If an object of height hoho is placed at a distance $u$ from the lens, and the image is formed at a distance $v$,

• Then the image size hihi is calculated as above.

In this example, the image size is found to be 3 mm, which corresponds to option (2).

Summary Table

Conclusion

The retinal image size for a 1.5 m tall object placed 8.5 m from the eye, with image distance of 1.7 cm from the lens, is approximately 3 mm.

Answer: (2) 3 mm