Why is a normal eye not able to see clearly the objects placed closer than 25 cm?

What is hypermetropia?

Can visible light be scattered by atoms/molecules in the earth’s atmosphere?

Why do different colours deviate through different angles on passing through a prism?

What is the function of the optic nerve in the human eye?

Why are we not able to see things clearly when we come out of a dark room?

Why do we observe random wavering or flicking of the objects near a fire or on a very hot day?

State the role of the eye lenses in the human eye?

Why is a convex lens called a converging lens?

What is the role of the ciliary muscles?

State the difference in colours of the sun observed during sunrise/sunset and noon. Give explanation for each.

Why does the sun appear reddish early in the morning? Will this phenomenon be observed by an astronaut on the Moon? Give reason to justify your answer.

Why is Tyndall effect shown by colloidal particles? State four instance of observing the Tyndall effect.

What is a spectrum? How can we recombine the components of white light after a glass prism has separated them?

A student is unable to see clearly the words written on the black board placed at a distance of approximately 3 m from him. Name the defect of vision the boy is suffering from. State the possible causes of this defect and explain the method of correcting it.

Name the three common defects of vision. What are their causes? Name the type of lens used to correct each of them.

List two causes of hypermetropia.

Write the function of retina in human eye.

List the parts of the human eye that control the amount of light entering into it. Explain how they perform this function?

Why does the sky appear dark instead of blue to an astronaut?

Explain why the planets do not twinkle.

Why do stars twinkle?

What happens to the image distance in the eye when we increase the distance of an object from the 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?

A person needs a lens of power –5.5 dioptres for correcting his distant vision. For correcting his near vision he needs a lens of power +1.5 dioptre. What is the focal length of the lens required for correcting (i) distant vision, and (ii) near vision?

The change in focal length of an eye lens is caused by the action of the (a) pupil. (b) retina. (c) ciliary muscles. (d) iris

The least distance of distinct vision for a young adult with normal vision is about (a) 25 m. (b) 2.5 cm. (c) 25 cm. (d) 2.5 m

The human eye forms the image of an object at its (a) cornea. (b) iris. (c) pupil. (d) retina.

The human eye can focus on objects at different distances by adjusting the focal length of the eye lens. This is due to (a) presbyopia. (b) accommodation. (c) near-sightedness. (d) far-sightedness

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?

What is the far point and near point of the human eye with normal vision?

A person with a myopic eye cannot see objects beyond 1.2 m distinctly. What should be the type of the corrective lens used to restore proper vision?

What is meant by power of accommodation of the eye?