Which part of the eye is responsible for adjusting the size of the pupil?

List two causes leading to myopia of the eye. Draw ray diagrams to show the image formation in case of a defective eye and a corrected eye.

How can a change in the size of the eyeball be a reason for $(a)$ Myopia and $(b)$ Hypermetropia? Compare the size of the eyeball with that of a normal eye in each case. How does this change in size affect the position of the image in each case?

What is meant by the spectrum of white light?

What is the twinkling of stars due to?

Explain the structure and functioning of the human eye. How are we able to see nearby as well as distant objects?