The Human Eyes And The Colourful World Science - The Human Eyes And The Colourful World

The change in focal length of an eye-lens is caused by the action of the:

The human eye forms the image of an object at its:

Which of the following colour of white light has the least wavelength?

The animal which does not have eyes that look sideways is:

The splitting up of white light into seven colours on passing through a glass prism is called:

Fill in the following blanks with suitable words:
To bring light from a distant object to a focus on the retina of the eye, the convex eye-lens needs to be made ____.

Fill in the following blanks with suitable words:
The iris controls the amount of _____ entering the eye.

Fill in the following blanks with suitable words:
When light is dim, the pupil becomes _____.

Fill in the following blanks with suitable words:
Most of the refraction of light rays entering the eye occurs at the outer surface of the _____.

Fill in the following blanks with suitable words:
The part of eye which alters the size of the pupil is ______.

State whether the following statements are true or false:

1. The scattering away of red light makes the sky appear blue during the day time.
2. The scattering away of blue light makes the sun appear red at sunset.

State whether the following statement is true or false:
Rabbit has eyes which look sideways.

State whether the following statement is true or false:
The planets twinkle at night due to atmospheric refraction of light.

What kind of lens is present in the human eye?

Give the scientific names of the following parts of the eye:
A hole in the middle of the iris.

Name some everyday objects:
which absorb all the colours in sunlight.

Name one defect of vision (or eye) which cannot be corrected by any type of spectacle lenses.

What type of lens is used to correct:

1. Hypermetropia?
2. Myopia?

What are the advantages of having two eyes instead of just one?

Complete the following statements:
When the sun is setting, the light from it has to travel a ____ thickness of the earth's atmosphere and only ____ wavelength _____ light is able to reach us. Sunset is therefore ___.

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

What shape are your eye-lenses:

1. When you look at your hand?
2. When you look at a distant tree?

Ciliary muscles of human eye can contract or relax. How does it help in the normal functioning
of the eye?

A student claims that because of atmospheric refraction, the sun can be seen after it has set, and the day is, therefore, longer than if the earth had no atmosphere.

1. What does the student mean by saying that the sun can be seen after it has set?
2. Do you think that the students conclusion is correct?

A person suffering from the eye-defect myopia (short-sightedness) can see clearly only up to a distance of 2 metres. What is the nature and power of lens required to rectify this defect?

Explain with the help of labelled ray diagram, the defect of vision called myopia and how it is corrected by a lens.

In the figure given alongside, a narrow beam of white light is shown to pass through a triangular glass prism. After passing through the prism, it produces a spectrum YX on the screen:
State the colour seen.

1. At X, and
2. At Y​​​​​​​​​​​​

​​​​​​​​​​​​

1. violet.
2. Red

2. ​​​​​​​Why do different colours of white light bend through different angles with respect to the incident beam of light?

Explain why, the planets do not twinkle at night?

Explain the functions of the following parts of the eye:

1. Iris.
2. Pupil.
3. Ciliary.
4. Muscles.
5. Eye-lens.
6. Retina.
7. Optic nerve.

The descriptions of five kinds of images are given below:

1. Diminished and virtual.
2. Enlarged and real.
3. Enlarged and erect.
4. Real and inverted.
5. Virtual and the same size.

Which one of these describes the image formed:

1. On the retina of the eye?
2. By a magnifying glass?
3. By a convex driving mirror on a car?
4. By a plane mirror?
5. on the screen of a slide projector?

What is short-sightedness? State the two causes of short-sightedness (or myopia). With the help of ray diagrams, show:

1. The eye-defect short-sightedness.
2. Correction of short-sightedness by using a lens.

What is long-sightedness? State the two causes of long-sightedness (or hypermetropia). With the help of ray diagrams, show:

1. The eye-defect long-sightedness.
2. Correction of long-sightedness by using a lens.

Differentiate between myopia and hypermetropia. What type of spectacles should be worn by a person having the defects of myopia as well as hypermetropia? How does it help?