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

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

Name the cells on the retina of an eye which are sensitive to

1. Dright light.
2. Dim light.
3. Sensation of colour.

The electronic configuration of an element is 2, 8, 4. State its:

1. Group and period in the modern periodic table.
2. Name and write its one physical property.

Why does the Sun appear reddish early in the morning?

No rainbow could be observed from the surface of Moon by the astronauts. What could be the possible reason?

Write the structure of eye lens and state the role of ciliary museles in the human eye.

The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct the problem?

What is spectrum? What is the name of glass shape used to produce a spectrum?

A man can read the number of a distant bus clearly but he finds difficulty in reading a book.A man can read the number of a distant bus clearly but he finds difficulty in reading a book.

1. From which defect of the eye is he suffering?
2. What type of spectacle lens should he use to correct the defect?

Give the function of the following.

1. Cornea.
2. Iris.