# Lakhmir Singh solutions for Class 10 Physics (Science) chapter 6 - The Human Eyes And The Colorful World [Latest edition]

## Solutions for Chapter 6: The Human Eyes And The Colorful World

Below listed, you can find solutions for Chapter 6 of CBSE Lakhmir Singh for Class 10 Physics (Science).

Exercise 1Exercise 2Exercise 3Exercise 4Exercise 5Exercise 6
Exercise 1 [Pages 269 - 272]

### Lakhmir Singh solutions for Class 10 Physics (Science) Chapter 6 The Human Eyes And The Colorful World Exercise 1 [Pages 269 - 272]

Exercise 1 | Q 1 | Page 269

What kind of lens is present in the human eye?

Exercise 1 | Q 2 | Page 269

Name two parts of the eye which refract light rays (or bend light rays).

Exercise 1 | Q 3.1 | Page 269

Name the part of the eye:

which controls the amount of light entering the eye.

Exercise 1 | Q 3.2 | Page 269

Name the part of the eye:

on which the image is formed.

Exercise 1 | Q 3.3 | Page 269

Name the part of the eye:

which changes the focal length of eye-lens.

Exercise 1 | Q 4.1 | Page 269

What is the name of:

the curved, transparent front surface of the eye?

Exercise 1 | Q 4.2 | Page 269

What is the name of:

the light-sensitive layer in the eye?

Exercise 1 | Q 5 | Page 269

Where is the image formed in a human eye?

Exercise 1 | Q 6 | Page 269

What is the function of the lens in the human eye?

Exercise 1 | Q 7 | Page 269

What job does the pupil of the eye do?

Exercise 1 | Q 8 | Page 269

How does the eye adjust to take account of an increase in brightness?

Exercise 1 | Q 9 | Page 269

Name that part of the eye which is equivalent to the photographic film in a camera.

Exercise 1 | Q 10 | Page 269

Name the part of the retina which is insensitive to light.

Exercise 1 | Q 12 | Page 269

Name two types of cells in the retina of an eye which respond to light.

Exercise 1 | Q 13.1 | Page 269

Out of rods and cones m the retina of your eye:

which detect colour?

Exercise 1 | Q 13.2 | Page 269

Out of rods and cones m the retina of your eye:

which work in dim light?

Exercise 1 | Q 14 | Page 269

State whether the following statement is true or false:
The image formed on our retina is upside-down

Exercise 1 | Q 15 | Page 270

What is the principal function of the eye-lens?

Exercise 1 | Q 16 | Page 270

Where does the greatest degree of refraction of light occur in the eye?

Exercise 1 | Q 17 | Page 270

What changes the shape of lens in the eye?

Exercise 1 | Q 18 | Page 270

What do the ciliary muscles do when you are focusing on a nearby object?

Exercise 1 | Q 18 | Page 270

What do the ciliary muscles do when you are focusing on a nearby object?

Exercise 1 | Q 19 | Page 270

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

Exercise 1 | Q 20.1 | Page 270

What is the:

far point of a normal human eye?

Exercise 1 | Q 20.2 | Page 270

What is the:

near point of a normal human eye?

Exercise 1 | Q 21 | Page 270

What is the range of vision of a normal human eye?

Exercise 1 | Q 22 | Page 270

Name the part of our eyes which helps us to focus near and distant objects in quick succession.

Exercise 1 | Q 23 | Page 279

Name the defect of vision which can be corrected by a converging lens. Show clearly by a ray diagram how the lens corrects the defect.

Exercise 1 | Q 24.1 | Page 270

Give the scientific names of the following parts of the eye:

carries signals from an eye to the brain.

Exercise 1 | Q 24.2 | Page 270

Give the scientific names of the following parts of the eye:

muscles which change the shape of the eye-lens.

Exercise 1 | Q 24.3 | Page 270

Give the scientific names of the following parts of the eye:

a hole in the middle of the iris.

Exercise 1 | Q 24.4 | Page 270

Fill in the following blank with suitable words:

When light is dim, the pupil becomes................

Exercise 1 | Q 24.4 | Page 270

Give the scientific names of the following parts of the eye:

a clear window at the front of the eye.

Exercise 1 | Q 24.5 | Page 270

Give the scientific names of the following parts of the eye:

changes shape to focus a picture on the retina.

Exercise 1 | Q 24.5 | Page 270

Fill in the following blank with suitable word:

The iris controls the amount of................entering the eye.

Exercise 1 | Q 25.1 | Page 270

Fill in the following blank with suitable word:

Most of the refraction of light rays entering the eye occurs at the outer surface of the.............

Exercise 1 | Q 25.2 | Page 270

Fill in the following blank with suitable word:

The part of eye sensitive to light is...................

Exercise 1 | Q 25.3 | Page 270

Fill in the following blank with suitable word:

The part of eye which alters the size of the pupil is............

Exercise 1 | Q 25.6 | Page 270

Fill in the following blank with suitable word:

To bring light from a distant object to a focus on the retina of the eye, the convex eye-lens needs to be made..........

Exercise 1 | Q 25.7 | Page 270

Fill in the following blank with suitable word:

To bring light from a near object to a focus on the retina of the eye, the convex eye-lens need­ to be made....................

Exercise 1 | Q 26 | Page 270

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

Exercise 1 | Q 27.1 | Page 270

What changes take place in the shape of eye-lens:

when the eye is focused on a near object?

Exercise 1 | Q 27.2 | Page 270

What changes take place in the shape of eye-lens:

when the eye is focused on a distant object?

Exercise 1 | Q 28.1 | Page 270

The eyes of a person are focused (i) on a nearby object, and (ii) on a distant object, turn by turn. In which case:

the focal length of eye-lens will be the maximum?

Exercise 1 | Q 28.2 | Page 270

The eyes of a person are focused (i) on a nearby object, and (ii) on a distant object, turn by turn. In which case:

the converging power of eye-lens will be the maximum?

Exercise 1 | Q 29 | Page 270

What change is made in the eye to enable it to focus on objects situated at different distances? Illustrate your answer with the help of diagrams.

Exercise 1 | Q 30 | Page 270

How is the amount of light entering the eye controlled?

Exercise 1 | Q 31 | Page 270

What happens to the eye when you enter a darkened cinema hall from bright sunshine? Give reason for your answer.

Exercise 1 | Q 32 | Page 270

Why does it take some time to see objects in a dim room when you enter the room from bright sunshine outside?

Exercise 1 | Q 33.1 | Page 271

A person walking in a dark corridor enters into a brightly lit room:

State the effect on the pupil of the eye.

Exercise 1 | Q 33.2 | Page 271

How does this affect the amount of light entering the eye?

Exercise 1 | Q 34 | Page 271

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

Exercise 1 | Q 35 | Page 271

Describe and explain, how a normal eye can see objects lying at various distances clearly.

Exercise 1 | Q 36.1 | Page 270

There are two types of light-sensitive cells in the human eye:

Where are they found?

Exercise 1 | Q 36.2 | Page 271

There are two types of light-sensitive cells in the human eye:

What is each type called?

Exercise 1 | Q 36.3 | Page 271

There are two types of light-sensitive cells in the human eye:

To what is each type of cell sensitive?

Exercise 1 | Q 37 | Page 271

What are rods and cones in the retina of an eye? Why is our night vision relatively poor compared to the night vision of an owl?

Exercise 1 | Q 38.1 | Page 271

How does the convex eye-lens differ from the ordinary convex lens made of glass?

Exercise 1 | Q 38.2 | Page 271

List, in order, the parts of the eye through which light passes to reach the retina.

Exercise 1 | Q 39.1 | Page 271

What happens to the size of pupil of our eye (i) in dim light (ii) in bright light?

Exercise 1 | Q 39.2 | Page 271

Name the cells on the retina of an eye which are sensitive to (i) bright light (ii) dim light (iii) sensation of colour.

Exercise 1 | Q 40.1 | Page 271

Draw a simple diagram of the human eye and label clearly the cornea, iris, pupil, ciliary muscles, eye-lens, retina, optic nerve and blind spot.

Exercise 1 | Q 40.2 | Page 271

Describe the working of the human eye with the help of the above diagram.

Exercise 1 | Q 40.3 | Page 271

How does the eye adjust itself to deal with light of varying intensity?

Exercise 1 | Q 41.1 | Page 271

Explain the functions of the following parts of the eye:
(i) cornea
(ii) iris
(iii) pupil
(iv) ciliary muscles
(v) eye-lens

Exercise 1 | Q 41.2 | Page 271

If you walk from a dark room into sunlight and back again into dark room, how would your pupils alter in size? What makes this happen?

Exercise 1 | Q 41.3 | Page 271

Explain why, we cannot see our seats first when we enter a darkened cinema hall from bright light but gradually they become visible.

Exercise 1 | Q 42 | Page 271

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

• cornea

• iris

• pupil

• retina

Exercise 1 | Q 43 | Page 271

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

• pupil

• retina

• ciliary muscles

• iris

Exercise 1 | Q 44 | Page 271

The least distance of distinct vision for a young adult with normal vision is about

• 25m

• 2.5cm

• 25cm

• 2.5m

Exercise 1 | Q 45 | Page 271

Refraction of light in the eye occurs at:
(a) the lens only
(b) the cornea only
(c) both the cornea and the lens
(d) the pupil

Exercise 1 | Q 46 | Page 271

To focus the image of a nearby object on the retina of an eye:
(a) the distance between eye-lens and retina is increased
(b) the distance between eye-lens and retina is decreased
(c) the thickness of eye-lens is decreased
(d) the thickness of eye-lens is increased

Exercise 1 | Q 47 | Page 271

The term " accommodation" as applied to the eye, refers to its ability to:
(a) control the light intensity falling on the retina
(b) erect the inverted image formed on the retina
(c) vary the focal length of the lens
(d) vary the distance between the lens and retina

Exercise 1 | Q 48 | Page 271

Which of the following controls the amount of light entering the eye?
(a) ciliary muscles
(b) lens
(c) iris
(d) cornea

Exercise 1 | Q 49 | Page 272

The human eye possesses the power of accommodation. This is the power to:
(a) alter the diameter of the pupil as the intensity of light changes
(b) distinguish between lights of different colours
(c) focus on objects at different distances
(d) decide which of the two objects is closer.

Exercise 1 | Q 50 | Page 272

How does the eye change in order to focus on near or distant objects?
(a) The lens moves in or out
(b) The retina moves in or out
(c) The lens becomes thicker or thinner
(d) The pupil gets larger or smaller

Exercise 1 | Q 51 | Page 272

Which of the following changes occur when you walk out of bright sunshine into a poorly lit room?
(a) the pupil becomes larger
(b) the lens becomes thicker
(c) the ciliary muscle relaxes
(d) the pupil becomes smaller

Exercise 1 | Q 52 | Page 272

The size of the pupil of the eye is adjusted by:
(a) cornea
(b) ciliary muscles
(c) optic nerve
(d) iris

Exercise 1 | Q 53 | Page 272

The descriptions of five kinds of images are given below:
(a) diminished and virtual
(b) enlarged and real
(c) enlarged and erect
(d) real and inverted
(e) virtual and the same size
Which one of these describes the image formed:
(i) on the retina of the eye?
(ii) by a magnifying glass?
(iii) by a convex driving mirror on a car?
(iv) by a plane mirror?
(v) on the screen of a slide projector?

Exercise 1 | Q 54.1 | Page 272

when you look at your hand?

Exercise 1 | Q 54.2 | Page 272

when you look at a distant tree?

Exercise 1 | Q 55 | Page 272

Suggest how your irises help to protect the retinas of your eyes from damage by bright light.

Exercise 1 | Q 56 | Page 272

Which parts of the eye cause rays of light to converge on the retina?

Exercise 1 | Q 56.2 | Page 272

Which part causes the greatest convergence?

Exercise 1 | Q 56.3 | Page 272

Which part brings the image into sharp focus on the retina? How does it do this?

Exercise 1 | Q 57 | Page 272

An object is moved closer to an eye. What changes must take place in the eye in order to keep the image in sharp focus?

Exercise 1 | Q 58 | Page 272

Why does the eye-lens not have to do all the work of converging incoming light rays?

Exercise 1 | Q 59 | Page 272

Explain why, when it is getting dark at night, it is impossible to make out the colour of cars on the road.

Exercise 1 | Q 60 | Page 272

Nocturnal animals (animals which sleep during the day and come out at night) tend to have  wide pupils and lot of rods in their retinas. Suggest reasons for this.

Exercise 2 [Pages 279 - 281]

### Lakhmir Singh solutions for Class 10 Physics (Science) Chapter 6 The Human Eyes And The Colorful World Exercise 2 [Pages 279 - 281]

Exercise 2 | Q 1 | Page 279

Name one of the common defects of vision and the type of lens used to remove it.

Exercise 2 | Q 2.1 | Page 279

Name the defect of vision in a person:

whose near point is more than 25 on away.

Exercise 2 | Q 2.2 | Page 279

Name the defect of vision in a person:

whose far point is less than infinity

Exercise 2 | Q 3.1 | Page 279

Which defect of vision can be rectified:

by using a concave lens?

Exercise 2 | Q 3.2 | Page 279

Which defect of vision can be rectified:

by using a convex lens?

Exercise 2 | Q 4.1 | Page 279

What type of lens is used to correct

myopia?

Exercise 2 | Q 4.2 | Page 279

What type of lens is used to correct

hypermetropia

Exercise 2 | Q 5.1 | Page 279

What is the other name for

myopia

Exercise 2 | Q 5.2 | Page 279

What is the other name for

hypermetropia

Exercise 2 | Q 6.1 | Page 279

What is the scientific name of

short-sightedness

Exercise 2 | Q 6.2 | Page 279

What is the scientific name of

long-sightedness?

Exercise 2 | Q 7.1 | Page 279

What kind of lens is used to correct

short-sightedness

Exercise 2 | Q 7.2 | Page 279

What kind of lens is used to correct

long-sightedness?

Exercise 2 | Q 8 | Page 279

State whether the following statement is true or false:
Short-sightedness can be cured by using a concave lens.

Exercise 2 | Q 9 | Page 279

Name the defect of vision in which the eye-lens loses its power of accommodation due to old age.

Exercise 2 | Q 10 | Page 279

Name the defect of vision which makes the eye-lens cloudy resulting in blurred vision.

Exercise 2 | Q 11 | Page 279

What is the other name of old age hypermetropia?

Exercise 2 | Q 12 | Page 279

Name any two defects of vision which can be corrected by using spectacles.

Exercise 2 | Q 13 | Page 279

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

Exercise 2 | Q 14 | Page 279

Name the body part with which the terms myopia and hypermetropia are connected.

Exercise 2 | Q 15 | Page 279

What is the far point of a person suffering from myopia (or short-sightedness)?

Exercise 2 | Q 16 | Page 279

Where is the near point of a person suffering from hypermetropia (or long-sightedness)?

Exercise 2 | Q 17.1 | Page 279

Your friend can read a book perfectly well but cannot read the writing on blackboard unless she sits on the front row in class.

Is she short-sighted or long-sighted?

Exercise 2 | Q 17.2 | Page 279

Your friend can read a book perfectly well but cannot read the writing on blackboard unless she sits on the front row in class.

What type of lenses-converging or diverging-would an optician prescribe for her?

Exercise 2 | Q 18.1 | Page 279

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

From which defect of the eye is he suffering?

Exercise 2 | Q 18.2 | Page 279

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

What type of spectacle lens should he use to correct the  defect?

Exercise 2 | Q 19.1 | Page 279

A student sitting in the last row of the class-room is not able to read clearly the writing on the blackboard.

Name the type of defect he is suffering from.

Exercise 2 | Q 19.2 | Page 279

A student sitting in the last row of the class-room is not able to read clearly the writing on the blackboard.

How can this defect by corrected?

Exercise 2 | Q 20.1 | Page 279

Complete the following sentence:

A short-sighted person cannot see ............ objects clearly. Short-sightedness can be corrected by using ........... lenses.

Exercise 2 | Q 20.2 | Page 279

Complete the following sentence.

A long-sighted person cannot see ........... objects clearly. Long-sightedness can be corrected by using .............. lenses.

Exercise 2 | Q 21 | Page 279

What are the two most common defects of vision (or defects of eye)? How are they corrected?

Exercise 2 | Q 22 | Page 279

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?

Exercise 2 | Q 24 | Page 280

Name the defect of vision which can be corrected by a diverging lens. Show clearly by a ray diagram how the lens corrects the defect.

Exercise 2 | Q 25 | Page 280

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

Exercise 2 | Q 26 | Page 280

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

Exercise 2 | Q 27 | Page 280

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?

Exercise 2 | Q 28 | Page 280

The near-point of a person suffering from hypermetropia is at 50 cm from his eye. What is the nature and power of the lens needed to correct this defect? (Assume that the near-point of the normal eye is 25 cm).

Exercise 2 | Q 29 | Page 280

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?

Exercise 2 | Q 30 | Page 280

What is presbyopia? Write two causes of this defect. Name the type of lens which can be used to correct presbyopia.

Exercise 2 | Q 31 | Page 280

When is a person said to have developed cataract in his eye? How is the vision of a person having cataract restored?

Exercise 2 | Q 32 | Page 280

fill in the following blank with suitable word:
A person is short-sighted if his eyeball is too............Spectacles with a .............lens are needed. A person is long-sighted if his eyeball is too............Spectacles with a ................lens are needed. These focus light rays exactly on to the..........

Exercise 2 | Q 33.1 | Page 280

What is short-sightedness? State the two causes of short-sightedness (or myopia). With the help of ray diagrams, show:
(i) the eye-defect short-sightedness.
(ii) correction of short-sightedness by using a lens.

Exercise 2 | Q 33.2 | Page 280

A person having short-sight cannot see objects clearly beyond a distance of 1.5 m. What would be the nature and power of the corrective lens to restore proper vision?

Exercise 2 | Q 34.1 | Page 280

What is long-sightedness? State the two causes of long-sightedness (or hypermetropia). With the help of ray diagrams, show:
(i) the eye-defect long-sightedness.
(ii) correction of long-sightedness by using a lens.

Exercise 2 | Q 34.2 | Page 280

An eye has a near point distance of 0.75 m. What sort of lens in spectacles would be needed to reduce the near point distance to 0.25 m? Also calculate the power of lens required. Is this eye long-sighted or short-sighted?

Exercise 2 | Q 34.3 | Page 280

An eye has a far point of 2 m. What type of lens in spectacles would be needed to increase the far point to infinity?  Also calculate the power of lens required. Is this eye long-sighted or short-sighted?

Exercise 2 | Q 35 | Page 280

The human eye can focus objects at different distances by adjusting the focal length of the eye lens. This is due to

• presbyopia

• accommodation

• near-sightedness

• far-sightedness

Exercise 2 | Q 36 | Page 280

The defect of vision which cannot be corrected by using spectacles is:
(a) myopia
(b) presbyopia
(c) cataract
(d) hypermetropia

Exercise 2 | Q 37 | Page 280

A person cannot see the distant objects clearly (though he can see the nearby objects clearly). He is suffering from the defect of vision called:
(a) cataract
(b) hypermetropia
(c) myopia
(d) presbyopia

Exercise 2 | Q 38 | Page 280

Though a woman can see the distant object clearly, she cannot see the nearby objects clearly. She is suffering from the defect of vision called:
(a) long-sight
(b) short-sight
(c) hind-sight
(d) mid-sight

Exercise 2 | Q 39 | Page 280

A young man has to hold a book at arm's length to be able to read it clearly. The defect of vision is:
(a) astigmatism
(b) myopia
(c) presbyopia
(d) hypermetropia

Exercise 2 | Q 40 | Page 281

After testing the eyes of a child, the optician has prescribed the following lenses for his spectacles:
Left eye : + 2.00 D
Right eye : + 2.25 D
The child is suffering from the defect of vision called:
(a) short-sightedness
(b) long-sightedness
(c) cataract
(d) presbyopia

Exercise 2 | Q 41 | Page 281

A person got his eyes tested. The optician's prescription for the spectacles reads:
Left eye: − 3.00 D
Right eye: − 3.50 D
The person is having a defect of  vision called:
(a) presbyopia
(b) myopia
(c) astigmatism
(d) hypermetropia

Exercise 2 | Q 42 | Page 281

A student sitting on the last bench in the class cannot read the writing on the blackboard clearly but he can read the book lying on his desk clearly. Which of the following statement is correct about the student?
(a) The near point of his eyes has receded away.
(b) The near point of his eyes has come close to him.
(c) The far point of his eyes has receded away.
(d) The far point of his eyes has come closer to him.

Exercise 2 | Q 43 | Page 281

A man driving a car can read a distant road sign clearly but finds difficulty in reading the odometer on the dashboard of the car. Which of the following statement is correct about this man?
(a) The near point of his eyes has receded away.
(b) The near point of his eyes has come closer to him.
(c) The far point of his eyes has receded away.
(d) The far point of his eyes has come closer to him.

Exercise 2 | Q 44 | Page 281

The defect of vision in which the eye-lens of a person gets progressively cloudy resulting in blurred vision is called:
(a) myopia
(b) presbyopia
(c) colourblindness
(d) cataract

Exercise 2 | Q 45 | Page 281

A person cannot see distant objects clearly. His vision can be corrected by using the spectacles containing:
(a) concave lenses
(b) plane lenses
(c) contact lenses
(d) convex lenses

Exercise 2 | Q 46 | Page 281

A person finds difficulty in seeing nearby objects clearly. His vision can be corrected by using spectacles containing:
(a) converging lenses
(b) diverging lenses
(c) prismatic lenses
(d) chromatic lenses

Exercise 2 | Q 47 | Page 281

In a certain murder investigation, it was important to discover whether the victim was long-sighted or short-sighted. How could a detective decide by examining his spectacles?

Exercise 2 | Q 48 | Page 281

The picture given here shows a person wearing 'half-moon' spectacles. What sort of eye-defect do do you think he has? Why are these particular spectacles useful to him?

Exercise 2 | Q 49 | Page 281

A short-sighted person has a near point of 15 cm and a far point of 40 cm.
(a) Can he see clearly an object at a distance of:
(i) 5 cm?
(ii) 25 cm?
(iii) 50 cm?
(b) To see clearly an object at infinity, what kind of spectacle lenses does he need?

Exercise 2 | Q 50.1 | Page 281

The near point of a long-sighted person is 50 cm from the eye.
(a) Can she see clearly an object at:
(i) a distance of 20 cm?
(ii) at infinity?

Exercise 2 | Q 50.2 | Page 281

To read a book held at a distance of 25 cm, will she need converging or diverging spectacle lenses?

Exercise 2 | Q 51.1 | Page 281

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

Exercise 2 | Q 51.2 | Page 281

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

if the person is a young man

Exercise 3 [Pages 283 - 288]

### Lakhmir Singh solutions for Class 10 Physics (Science) Chapter 6 The Human Eyes And The Colorful World Exercise 3 [Pages 283 - 288]

Exercise 3 | Q 1.1 | Page 283

How much is our field of view:

with one eye open?

Exercise 3 | Q 1.2 | Page 283

How much is our field of view:

with both eyes open?

Exercise 3 | Q 2 | Page 283

Which of the following have a wider field of view?
(a) Animals having two eyes on the opposite sides of their head.
(b) Animals having two eyes at the front of their head.

Exercise 3 | Q 3.1 | Page 283

Out of animals of prey and predators, which have their eyes:

at the front of their head?

Exercise 3 | Q 3.2 | Page 283

Out of animals of prey and predators, which have their eyes:

on the opposite sides of their head?

Exercise 3 | Q 4 | Page 283

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

Exercise 3 | Q 5.1 | Page 284

Fill in the following blank with suitable word:

Having two eyes gives a ................field of view.

Exercise 3 | Q 5.2 | Page 284

Fill in the following blank with suitable word:

Having two eyes enables us to judge.................more accurately.

Exercise 3 | Q 6 | Page 284

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

Exercise 3 | Q 7 | Page 284

Explain clearly why, a person who has lost the sight of one eye is at a disadvantage compared with the normal person who has two good eyes.

Exercise 3 | Q 8.1 | Page 284

Name two animals having eyes:

one the sides of the head.

Exercise 3 | Q 8.2 | Page 284

Name two animals having eyes:

at the front of the head.

Exercise 3 | Q 9 | Page 284

Among animals, the predators (like lions) have their eyes facing forward at the front of their heads, whereas the animals of prey (like rabbit) usually have eyes at the sides of their head. Why is this so?

Exercise 3 | Q 10.1 | Page 284

Five persons A, B, C, D and E have diabetes, leukaemia, asthma, meningitis and hepatitis, respectively.

Which of these persons can donate eyes?

Exercise 3 | Q 10.2 | Page 284

Five persons A, B, C, D and E have diabetes, leukaemia, asthma, meningitis and hepatitis, respectively.

Which of these persons cannot donate eyes?

Exercise 3 | Q 11 | Page 284

The animal which does not have eyes that look sideways is:
(a) Horse
(b) Chicken
(c) Lion
(d) Fish

Exercise 3 | Q 12 | Page 284

With both eyes open, a person's field of view is about:
(a) 90°
(b) 150°
(c) 180°
(d) 360°

Exercise 3 | Q 13 | Page 284

Having two eyes gives a person:
(a) deeper field of view
(b) coloured field of view
(c) rear field of view
(d) wider field of view

Exercise 3 | Q 14 | Page 284

The animals of prey have:
(a) two eyes at the front
(b) two eyes at the back
(c) two eyes on the sides
(d) one eye at the front and one on the side

Exercise 3 | Q 15 | Page 284

The animals called predators have:
(a) both the eyes on the sides
(b) one eye on the side and one at the front
(c) one eye on the front and one at the back
(d) both the eyes at the front

Exercise 3 | Q 16 | Page 288

(i) A ray of white light breaks up into its components while passing through a glass prism. Draw a ray diagram to show the path of rays.
(ii) Mark the least deviated colour in your  diagram

(iii) Why do different coloured rays deviate differently in a prism?

Exercise 4 [Pages 288 - 290]

### Lakhmir Singh solutions for Class 10 Physics (Science) Chapter 6 The Human Eyes And The Colorful World Exercise 4 [Pages 288 - 290]

Exercise 4 | Q 1 | Page 288

As light rays pass from air into a glass prism, are they refracted towards or away from the normal?

Exercise 4 | Q 2 | Page 288

As light rays emerge from a glass prism into air, are they refracted towards or away from the normal?

Exercise 4 | Q 3 | Page 288

Name a natural phenomenon which is caused by the dispersion of sunlight in the sky.

Exercise 4 | Q 4 | Page 288

What information do we get about sunlight from the formation of a rainbow?

Exercise 4 | Q 5 | Page 288

What did Newton demonstrate by his experiments with the prism?

Exercise 4 | Q 6 | Page 288

What colours make up white light?

Exercise 4 | Q 7 | Page 288

Give the meaning of the term VIBGYOR. With which phenomenon is it connected?

Exercise 4 | Q 8.1 | Page 288

In the formation of spectrum of white light by a prism:

which colour is deviated least?

Exercise 4 | Q 8.2 | Page 288

In the formation of spectrum of white light by a prism:

which colour is deviated most?

Exercise 4 | Q 9 | Page 288

What colours lie on the two sides of the 'green colour' in the spectrum of white light?

Exercise 4 | Q 10 | Page 288

Name the scientist who discovered that sunlight consists of seven colours.

Exercise 4 | Q 11 | Page 288

What is the order of colours in a rainbow, from the outside to the inside?

Exercise 4 | Q 11 | Page 288

Find the position and nature of the image of an object 5 cm high and 10 cm in front of a convex lens of focal length 6 cm.

Exercise 4 | Q 12.1 | Page 288

Which colour of the spectrum has

longest wavelength,

Exercise 4 | Q 12.2 | Page 288

Which colour of the spectrum has

shortest wavelength?

Exercise 4 | Q 13 | Page 288

Which light has the longer wavelength : red light or blue light?

Exercise 4 | Q 14 | Page 288

Which colour of light has the shorter wavelength − red or violet?

Exercise 4 | Q 15.1 | Page 288

Fill in the blank with suitable word:

When a ray of light enters a prism, it bends ................ the normal ; as it leaves the prism, it bends ................. the normal.

Exercise 4 | Q 17.1 | Page 289

What happens when a ray of ordinary light is passed through a triangular glass prism?

Exercise 4 | Q 17.2 | Page 289

What will happen if another similar glass prism is placed upside down behind the first prism?

Exercise 4 | Q 18 | Page 289

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.

Exercise 4 | Q 19.1 | Page 289

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

Exercise 4 | Q 19.2 | Page 289

How many colours are there in a full spectrum of white light? Write the various colours of spectrum in the order, starting with red.

Exercise 4 | Q 20 | Page 289

What is meant by dispersion of white light? Describe the formation of rainbow in the sky with the help of a diagram.

Exercise 4 | Q 21.1 | Page 289

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 (i) at X, and (ii) at Y.

Exercise 4 | Q 21.2 | Page 289

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.

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

Exercise 4 | Q 22 | Page 289

Draw a diagram to show how white light can be dispersed into a spectrum by using a glass prism. Mark the various colours of the spectrum.

Exercise 4 | Q 23 | Page 289

Make two diagrams to explain refraction and dispersion.

Exercise 4 | Q 24 | Page 289

Describe how you could demonstrate that white light is composed of a number of colours.

Exercise 4 | Q 25 | Page 289

How could you show that the colours of the spectrum combine to give white light?

Exercise 4 | Q 26 | Page 289

Which is refracted most by a prism : red light or violet light? Explain why?

Exercise 4 | Q 27.1 | Page 289

Draw a diagram to show the refraction of light through a glass prism. On this diagram, mark
(i) incident ray
(ii) emergent ray, and
(iii) angle of deviation.

Exercise 4 | Q 27.2 | Page 289

What is a rainbow? What are the two conditions necessary for the formation of a rainbow in the sky?

Exercise 4 | Q 27.3 | Page 289

What acts as tiny prisms in the formation of a rainbow?

Exercise 4 | Q 27.4 | Page 289

Name the process which is involved in the formation of a rainbow.

Exercise 4 | Q 27.5 | Page 289

What are the seven colours seen in a rainbow?

Exercise 4 | Q 28 | Page 289

A beam of white light is shone onto a glass prism. The light cannot be:
(a) deviated
(b) dispersed
(c) focused
(d) refracted

Exercise 4 | Q 29 | Page 289

A beam of white light falls on a glass prism. The colour of light which undergoes the least bending on passing through the glass prism is:
(a) violet
(b) red
(c) green
(d) blue

Exercise 4 | Q 30 | Page 289

The colour of white light which suffers the maximum bending (or maximum refraction) on passing through a glass prism is:
(a) yellow
(b) orange
(c) red
(d) violet

Exercise 4 | Q 31 | Page 289

Which of the following colour of white light is least deviated by the prism?
(a) green
(b) violet
(c) indigo
(d) yellow

Exercise 4 | Q 32 | Page 289

The colour of white light which is deviated the maximum on passing through the glass prism is:
(a) blue
(b) indigo
(c) red
(d) orange

Exercise 4 | Q 33 | Page 289

The splitting up of white light into seven colours on passing through a glass prism is called:
(a) refraction
(b) deflection
(c) dispersion
(d) scattering

Exercise 4 | Q 34 | Page 289

Which of the following coloured light has the least speed in glass prism?
(a) violet
(b) yellow
(c) red
(d) green

Exercise 4 | Q 35 | Page 289

The coloured light having the maximum speed in glass prism is:
(a) blue
(b) green
(c) violet
(d) yellow

Exercise 4 | Q 36 | Page 289

Which of the following colour of white light has the least wavelength?
(a) red
(b) orange
(c) violet
(d) blue

Exercise 4 | Q 37 | Page 290

Out of the following, the colour of light having the maximum wavelength is:
(a) violet
(b) indigo
(c) green
(d) orange

Exercise 4 | Q 38 | Page 290

Why do you not see a spectrum of colours when light passes through a flat pane of glass?

Exercise 4 | Q 39.1 | Page 290

Name some everyday objects:

which reflect all the colours in sunlight

Exercise 4 | Q 39.2 | Page 290

Name some everyday objects:

which absorb all the colours in sunlight

Exercise 4 | Q 40 | Page 290

Where in nature can you find evidence that white sunlight may be made of different colours?

Exercise 5 [Pages 292 - 293]

### Lakhmir Singh solutions for Class 10 Physics (Science) Chapter 6 The Human Eyes And The Colorful World Exercise 5 [Pages 292 - 293]

Exercise 5 | Q 1 | Page 292

The phenomenon that causes the twinkling of stars is refraction of light.

Exercise 5 | Q 2 | Page 292

Name two effects produced by the atmospheric refraction.

Exercise 5 | Q 3.1 | Page 292

Which phenomenon makes us see the sun:

a few minutes before actual sunrise?

Exercise 5 | Q 3.2 | Page 292

Which phenomenon makes us see the sun:

a few minutes after actual sunset?

Exercise 5 | Q 4.1 | Page 292

Atmospheric refraction causes advance sunrise and delayed sunset. By how much time is:

Exercise 5 | Q 4.2 | Page 292

Atmospheric refraction causes advance sunrise and delayed sunset. By how much time is:

sunset delayed?

Exercise 5 | Q 5 | Page 292

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

Exercise 5 | Q 6 | Page 292

Name the phenomenon due to which the stars seem higher in the sky than they actually are.

Exercise 5 | Q 7 | Page 292

Fill in the following blank with suitable word:
We can see the sun about ................ minutes before the actual sunrise and about ................ minutes after the actual sunset because of atmospheric ................

Exercise 5 | Q 8 | Page 292

Why do stars seem higher than they actually are? Illustrate your answer with the help of a diagram.

Exercise 5 | Q 9 | Page 292

Explain why, the sun can be seen about two minutes before actual sunrise. Draw a diagram to Illustrate your answer.

Exercise 5 | Q 10 | Page 292

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

Exercise 5 | Q 11.1 | Page 292

What is atmospheric refraction? What causes atmospheric refraction?

Exercise 5 | Q 11.2 | Page 292

Why do stars twinkle on a clear night?

Exercise 5 | Q 11.3 | Page 292

Explain why, the planets do not twinkle at night.

Exercise 5 | Q 12 | Page 292

The twinkling of stars is due to atmospheric:
(a) reflection of light
(b) dispersion of light
(c) interference of light
(d) refraction of light

Exercise 5 | Q 13 | Page 293

The atmospheric refraction of light causes the twinkling of:
(a) planets only
(b) stars only
(c) planets and stars
(d) stars and satellites

Exercise 5 | Q 14 | Page 293

The stars appear higher in the sky than they actually are, due to:
(a) diffraction of light
(b) scattering of light
(c) refraction of light
(d) reflection of light

Exercise 5 | Q 15 | Page 293

The stars twinkle but the planets do not twinkle at night because:
(a) the stars are small but the planets are large
(b) the stars are very large but planets are small
(c) the stars are much nearer but planets are far off
(d) the stars are far off but planets are nearer to earth

Exercise 5 | Q 16 | Page 293

As light from a far off star comes down towards the earth:
(a) it bends away from the normal
(b) it bends towards the normal
(c) it does not bend at all
(d) it is reflected back

Exercise 5 | Q 17 | Page 293

We can see the sun before the actual sunrise by about:
(a) 5 minutes
(b) 2 minutes
(c) 2 hours
(d) 20 minutes

Exercise 5 | Q 18 | Page 293

Due to atmospheric refraction of sunlight, the time from sunrise to sunset is lengthened by about:
(a) 6 minutes
(b) 2 minutes
(c) 4 minutes
(d) 5 minutes

Exercise 5 | Q 19 | Page 293

The day is longer on the earth by about 4 minutes because:
(a) the earth is round in shape
(b) the earth rotates on its axis
(c) the earth revolves around the sun
(d) the earth has atmosphere

Exercise 5 | Q 20 | Page 293

We know that light refracts (or bends) when it goes from one medium to another. Now, the atmosphere contains only air. Then how does light get refracted on passing through only air in the atmosphere?

Exercise 5 | Q 21 | Page 293

By how much time the day would have been shorter if the earth had no atmosphere?

Exercise 5 | Q 22.1 | Page 293

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.

What does the student mean by saying that the sun can be seen after it has set?

Exercise 5 | Q 22.2 | Page 293

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.

Do you think that the students conclusion is correct?

Exercise 6 [Pages 297 - 298]

### Lakhmir Singh solutions for Class 10 Physics (Science) Chapter 6 The Human Eyes And The Colorful World Exercise 6 [Pages 297 - 298]

Exercise 6 | Q 1.1 | Page 297

What is the colour of the sunlight:

scattered by the dust particles in the atmosphere?

Exercise 6 | Q 1.2 | Page 297

What is the colour of the sunlight

scattered by the air molecules in the atmosphere?

Exercise 6 | Q 2 | Page 297

Which of the two is scattered more easily : light of shorter wavelengths or light of longer wavelengths?

Exercise 6 | Q 3.1 | Page 297

State whether the following statements are true or false:

The scattering away of red light makes the sky appear blue during the day time.

Exercise 6 | Q 3.2 | Page 297

State whether the following statements are true or false:

The scattering away of blue light makes the sun appear red at sunset.

Exercise 6 | Q 4 | Page 297

What colour does the sky appear to an astronaut?

Exercise 6 | Q 5 | Page 297

Which effect is illustrated by the observation that when a beam of sunlight enters a dusty room, then its path becomes visible to us.

Exercise 6 | Q 6 | Page 297

State two effects produced by the scattering of light by the atmosphere.

Exercise 6 | Q 7 | Page 297

What is tyndall effect? Explain with an example.

Exercise 6 | Q 8 | Page 297

What happens when a beam of sunlight enters a dusty room through a window? Explain your answer.

Exercise 6 | Q 9 | Page 298

Why does the sky appear blue on a clear day?

Exercise 6 | Q 10 | Page 298

Why does the sky appear dark (or black) to an astronaut instead of blue?

Exercise 6 | Q 11 | Page 298

Why does sun appear red at sunrise and sunset?

Exercise 6 | Q 12 | Page 298

Why does the sun appear red at sunset?

Exercise 6 | Q 13 | Page 298

Why are the 'danger signal' lights red in colour?

Exercise 6 | Q 14.1 | Page 298

Draw a neat and labelled diagram of the experimental set up for observing the scattering of light in a colloidal solution of sulphur to show how the sky appears blue, and the sun appears red at sunrise and sunset.

Exercise 6 | Q 14.2 | Page 298

Out of blue light and red light, which one is scattered more easily?

Exercise 6 | Q 14.3 | Page 298

Which component of sunlight is scattered away when the sun appears red at sunrise or sunset?

Exercise 6 | Q 14.4 | Page 298

What causes the scattering of blue component of sunlight in the atmosphere?

Exercise 6 | Q 15 | Page 298

The blue colour of sky is due to:
(a) refraction of light
(b) dispersion of light
(c) diffraction of light
(d) scattering of light

Exercise 6 | Q 16 | Page 298

The red colour of the sun at the time of sunrise and sunset is because:
(a) red colour is least scattered
(b) blue colour is least scattered
(c) red colour is most scattered
(d) blue colour is most scattered

Exercise 6 | Q 17 | Page 298

Which of the following is not caused by the atmospheric refraction of light?
(a) twinkling of stars at night
(b) sun appearing higher in the sky than it actually is
(c) sun becoming visible two minutes before actual sunrise
(d) sun appearing red at sunset

Exercise 6 | Q 18 | Page 298

The sky appears blue because some of the blue component of sunlight is scattered by:
(a) gas molecules present in air
(b) dust particles present in air
(c) water droplets suspended in air
(d) soot particles present in air

Exercise 6 | Q 19 | Page 298

Sunset is red because at that time the light coming from the sun has to travel:
(a) lesser thickness of earth's atmosphere
(b) greater thickness of earth's atmosphere
(c) varying thickness of earth's atmosphere
(d) along the horizon

Exercise 6 | Q 20.1 | Page 298

In an experiment to study the scattering of light by passing a beam of white light through a colloidal solution of sulphur in a transparent glass tank:

Which colour is observed from the front of the glass tank? Does this colour correspond to the colour of sky on a clear day or the colour of sky around the sun at sunset?

Exercise 6 | Q 20.2 | Page 298

In an experiment to study the scattering of light by passing a beam of white light through a colloidal solution of sulphur in a transparent glass tank:

Which colour is observed from the sides of the glass tank? Does this colour correspond to the colour of sky on a clear day or the colour of sky around the sun at sunset?

Exercise 6 | Q 21 | Page 298

Explain why, when the sun is overhead at noon, it appears white, but when the same sun is near the horizon at sunset, it appears red.

Exercise 6 | Q 22 | Page 298

Complete the following statement:
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 ................

Exercise 6 | Q 23 | Page 298

Define the term "power of accommodation" of human eye.

## Solutions for Chapter 6: The Human Eyes And The Colorful World

Exercise 1Exercise 2Exercise 3Exercise 4Exercise 5Exercise 6

## Lakhmir Singh solutions for Class 10 Physics (Science) chapter 6 - The Human Eyes And The Colorful World

Shaalaa.com has the CBSE Mathematics Class 10 Physics (Science) CBSE solutions in a manner that help students grasp basic concepts better and faster. The detailed, step-by-step solutions will help you understand the concepts better and clarify any confusion. Lakhmir Singh solutions for Mathematics Class 10 Physics (Science) CBSE 6 (The Human Eyes And The Colorful World) include all questions with answers and detailed explanations. This will clear students' doubts about questions and improve their application skills while preparing for board exams.

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Concepts covered in Class 10 Physics (Science) chapter 6 The Human Eyes And The Colorful World are Spherical Mirrors, Concave Mirror, Convex Mirror, Concave Lens, Refraction of Light, Image Formation by Convex Mirror, Sign Convention for Reflection by Spherical Mirrors, Mirror Equation/Formula, Images Formed by Spherical Mirrors, Image Formation by Concave Mirror, Reflection of Light, Law of Reflection of Light, Linear Magnification (M) Due to Spherical Mirrors, Magnification Due to Spherical Lenses, Power of a Lens, Mirrors and Its Types, Plane Mirror and Reflection, Rules for the Construction of Image Formed by a Spherical Mirror, Refraction of Light Through a Rectangular Glass Slab, Law of Refraction of Light, Refractive Index, Spherical Lens, Images Formed by Sperical Lenses, Guideline for Image Formation Due to Refraction Through a Convex and Concave Lens, Images Formed Due to Refraction Through a Concave Lens, Convex Lens, Images Formed Due to Refraction Through a Convex Lens, Sign Convention for Spherical Lenses, Lens Formula, Spherical Mirrors, Concave Mirror, Convex Mirror, Concave Lens, Refraction of Light, Image Formation by Convex Mirror, Sign Convention for Reflection by Spherical Mirrors, Mirror Equation/Formula, Images Formed by Spherical Mirrors, Image Formation by Concave Mirror, Reflection of Light, Law of Reflection of Light, Linear Magnification (M) Due to Spherical Mirrors, Magnification Due to Spherical Lenses, Power of a Lens, Mirrors and Its Types, Plane Mirror and Reflection, Rules for the Construction of Image Formed by a Spherical Mirror, Refraction of Light Through a Rectangular Glass Slab, Law of Refraction of Light, Refractive Index, Spherical Lens, Images Formed by Sperical Lenses, Guideline for Image Formation Due to Refraction Through a Convex and Concave Lens, Images Formed Due to Refraction Through a Concave Lens, Convex Lens, Images Formed Due to Refraction Through a Convex Lens, Sign Convention for Spherical Lenses, Lens Formula.

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