What is the least distance of distinct vision of a normal human eye (in $cm$)?

The compound microscope consists of two convex lenses of $5 \, cm$ and $20 \, cm$ focal length. Which of them will be the objective and the eyepiece?

What is the lens placed near the eye in a compound microscope called?

Name the outermost layer of the eye. What is its function?

For a person suffering from myopia,the image of the object is formed in front of the retina.

$A$ person is unable to read a book clearly when kept at a distance of $25 \,cm$ from his eye. Name the defect. How can it be corrected? Draw ray diagrams for $(i)$ defective eye $(ii)$ corrected eye and explain them.