A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from? How can it be corrected?

Write the function of the retina in the human eye.

Explain why, if we look at objects through the hot air over a fire, the objects appear to be moving (or shaking) slightly.

Name the part of the eye where the image is formed by the eye lens. What is the nature of the image formed? How is this image sent to the brain?

Why do stars twinkle?

Write the function of each of the following parts of human eye.

1. Cornea.
2. Iris.
3. Crystalline lens.
4. Ciliary muscles.

When a beam of white light is passed through a prism, it splits to form lights of seven colours. Is it possible to recombine the lights of seven colours to obtain the white light again? Explain your answer.

Why does the sun appear red at sunrise?

Explain the nature of image formed by human eye lens.

A person can read a book clearly only if he holds it at an arm's length from him. Name the defect of vision:

1. If the person is an old man.
2. If the person is a young man.