A person suffering from an eye defect uses lenses of power – 1D. Name the defect he is suffering from and the nature of lens used.

Name the:

a. Component of white light that deviates the least.

b. Component of white light that deviates the most, while passing through a glass prism.

State the function of pupil of an eye.

Name the two phenomenons involved in the formation of rainbow.

List the factors on which scattering of light depend.

Four students A, B, C and D were asked by their teacher to find the corresponding image distance for the given object distance keeping the object at various distance in case of a given convex lens of focal length 15 cm. The following observation were recorded by them.

Which student recorded the incorrect observation?

A student is unable to see clearly the words written on the blackboard placed at a distance of approximately 4 m from him. Name the defect of vision the boy is suffering from. Explain the method of correcting this defect Draw ray diagram for the:

i. defect of vision and also

ii. for its correction.

A person is unable to see objects nearer than 50 cm. He wants to read a book placed at a distance of 25 cm. Find the nature, focal length and power of the lens, he requires for his spectacles.

A person with a myopic eye cannot see objects beyond a distance of 1.5 m from it. What would be the nature and power of the corrective lens used to restore proper vision?

a. What is the least distance of distinct vision for a normal eye?

b. Does the above distance increase or decrease for a long- sighted eye? Give reason for your answer with diagram.

The adjoining diagram shows the path taken by a narrow beam of yellow monochromatic light passing through a 60° glass prism. Now the yellow light is replaced by a narrow beam of the white light incident at the same angle. Draw another ray diagram to show the passage of the beam through the prism and label it, to show the effect of the prism on the light.

Explain with the help of diagram why the sun is visible to us two minutes before the actual sunrise and two minutes after the sunset.

What is “dispersion of white light” ? Draw a labelled diagram to illustrate the recombination of the spectrum of white light. Why it is essential that the two prisms used for the purpose should be identical and placed in an inverted position with respect to each other?

Study the given diagram and answer the questions that follows:

i. Which defect of vision is represented in this case? Give a reason for your answer.

ii. What could be the two causes of this defect?

iii. With the help of a diagram showing how this defect can be corrected by the use of the suitable lens.

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

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

Give reasons for each of the following:

i. The sky appears dark instead of blue to an astronaut in space.

ii. The sky near the horizon appears to have a reddish hue at the time of sunset and sunrise.

iii. The stars appear to twinkle.

Write the functions of each of the following parts of the human eye:

i. Cornea

ii. Iris

iii. Crystalline (Eye) lens

iv. Ciliary muscles

v. Retina

A person is unable to see distinctly the objects closer than 1 m. Name the defect of vision he is suffering from. Draw ray diagrams to illustrate the cause of the defect and its correction by suitable lens.

A person is unable to see distinctly the words printed on a newspaper. Name the defect of vision he is suffering from. Draw ray diagram to illustrate this defect. List its two possible causes. Draw a ray diagram to show how this defect may be corrected using a lens of appropriate focal length.