The Human Eye and The Colourful World - Lakhmir Singh Manjit Kaur Solutions Pg No. 280 Class 10 Physics

Solutions of The Human Eye and The Colourful World Lakhmir Singh Manjit Kaur MCQ, HOTS, VSAQ and SAQ Pg No. 280 Class 10 Physics

Solutions of The Human Eye and The Colourful World Lakhmir Singh Manjit Kaur MCQ, HOTS, VSAQ and SAQ Pg No. 280 Class 10 Physics

Multiple Choice Questions (MCQs)-Pg-280

35. The human eye can focus 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

Answer


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

6. The defect of vision which cannot be corrected by using spectacles is :
A. myopia
B. presbyopia
C. cataract
D. hypermetropia

Answer

→ The defect of vision which cannot be corrected by using spectacles is cataract.

37. 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

Answer

→ 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 myopia.

38. Though a woman can see the distant objects 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

Answer

→ Though a woman can see the distant objects clearly, she cannot see the nearby objects clearly. She is suffering from the defect of vision called long-sightedness.

39. 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

Answer

→ A young man has to hold a book at arm's length to be able to read it clearly. The defect of vision is hypermetropia.

40. 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

Answer

→ The child is suffering from the defect of vision called long-sightedness.

41. 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

Answer

→ The person is having a defect of vision called myopia.

42. 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 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

Answer

→ 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. The far point of his eyes has come closer to him.

43. 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.

Answer

→ 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. It shows that, the near point of his eyes has receded away.

44. 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. colour blindness
D. cataract

Answer

→ The defect of vision in which the eye-lens of a person gets progressively cloudy resulting in blurred vision is called cataract

45. 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

Answer

→ A person cannot see distant objects clearly. His vision can be corrected by using the spectacles containing concave lenses.

46. 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

Answer

→ A person finds difficulty in seeing nearby objects clearly. His vision can be corrected by using spectacles containing converging lenses.

Questions Based on High Order Thinking Skills (HOTS)-Pg-281

47. 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?

Answer


→ The examination of the spectacles can be done by determining the type of lens used in it. If spectacle lenses are convex, the person was long-sighted but if spectacle lenses are concave, then the person was short-sighted.

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


Answer

→ The picture given here shows a person wearing 'half-moon' spectacles. The eye defect he may have is Long-sightedness (Hypermetropia). This particular spectacles help him because the convex lenses of spectacles form the image of nearby object at the near point of his eye.

49. 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 dearly an object at infinity, what kind of spectacle lenses does he need ?

Answer

→ (a) i) A short-sighted person has a near point of 15 cm and a far point of 40 cm. He cannot see an object clearly when it is at a distance of 5cm.
ii) A short-sighted person has a near point of 15 cm and a far point of 40 cm. He can see an object clearly when it is at a distance of 5cm.
iii) A short-sighted person has a near point of 15 cm and a far point of 40 cm. He can see an object clearly when it is at a distance of 50cm.
(b) To see clearly an object at infinity spectacles should must have a concave lenses.

50. The near point of a long-sighted person is 50 cm from the eye.
(a) Can she see dearly an object at:
(i) a distance of 20 cm ? (ii) at infinity ?
(b) To read a book held at a distance of 25 cm, will she need converging or diverging spectacle lenses?

Answer

→ (a) (i) The near point of a long-sighted person is 50 cm from the eye so he cannot see clearly an object at a distance of 20cm.
(ii) The near point of a long-sighted person is 50 cm from the eye so he cannot see clearly an object at infinity.
(b) To read a book held at a distance of 25 cm, she will need converging spectacle lens.

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

Answer

→ (a) Presbyopia is the name of the defect when a person can read a book dearly only if he holds it at an arm's length from him. In case of old man.
(b) Hypermetropia is the name of the defect when a person can read a book dearly only if he holds it at an arm's length from him. In case of a young man.

Very Short Answer Type Questions-Pg-283

1. How much is our field of view:
(a) with one eye open?
(b) with both eyes open?

Answer

→ (a) Our field of view with one eye open is about 150°
(b) Our field of view with both eye open is about 180°.

2. 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.

Answer

→ Animals having two eyes on the opposite sides of their head.

3. Out of animals of prey and predators, which have their eyes:
(i) at the front of their head?
(iii) on the opposite sides of their head?

Answer

→ (i) Out of animals of prey and predators who have their eyes at the front of their head are predators.
(ii) Out of animals of prey and predators who have their eyes on the opposite sides of their head are animal of prey.

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

Answer

→ True, Rabbit has eyes which look sideways.

5. Fill in the following blanks with suitable words:
(a) Having two eyes gives a ______ field of view.
(b) Having two eyes enables us to judge ______ more accurately.

Answer

→ (a) Having two eyes gives a wider field of view.
(b) Having two eyes enables us to judge distance more accurately.

Short Answer Type Questions-Pg-284

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

Answer


→ The advantages of having two eyes instead of just one is that one can see to about 180°.

7. 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.

Answer

→ A person who has lost the sight of one eye is at a disadvantage compared with the normal person who has two good eyes. This is because with one eye one can only see to about 1500 but with two eyes one can see about 1800.

8. Name two animals having eyes:
(a) on the sides of the head.
(b) at the front of the head.

Answer

→ (a) two animals having eyes on the side of the head are rabbit and deer.
(b) The two animals having eyes at the front of the head are Tiger and Lion.

9. 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?

Answer

→ The animals of prey (like rabbit) usually have eyes at the side of their head, because this gives them a larger field of view. So that they can see their enemy easily but the predators do not have such larger field of view.

10. Five persons A, B, C, D and E have diabetes, leukaemia, asthma, meningitis and hepatitis, respectively.
(a) Which of these persons can donate eyes?
(b) Which of these persons cannot donate eyes?

Answer

→ (a) The people with diabetes and asthma can donate their eyes.
(b) Person with leukaemia, meningitis and hepatitis cannot donate their eyes.

Multiple Choice Questions (MCQs)-Pg-284

11. The animal which does not have eyes that look sideways is:
A. Horse
B. Chicken
C. Lion
D. Fish

Answer


→ The animal which does not have eyes that look sideways is Lion.

12. With both eyes open, a person's field of view is about:
A. 90°
B. 150°
C. 180°
D. 360°

Answer

→ With both eyes open, a person's field of view is about 180°.

13. 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

Answer

→ Having two eyes gives a person wider field of view.

14. 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

Answer

→ The animals of prey have two eyes on the sides.

15. 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

Answer

→ The animals called predators have both the eyes at the front.

Very Short Answer Type Questions-Pg-288

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

Answer

→ As light rays pass from air into a glass prism, they got refracted towards the normal.

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

Answer

→ As light rays emerge from a glass prism into air, they got reflected away from the normal.

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

Answer

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

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

Answer

→ With the formation of the rainbow we got the information that sunlight consist of seven colors.

5. What did Newton demonstrate by his experiments with the prism?

Answer

→ The white light consist of a mixture of seven colors, demonstrated by his experiment with a prism.

6. What colours make up white light?

Answer

→ The seven color make up to form white light, which are Violet, indigo, blue, green, yellow, orange, red.

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

Answer

→ The term VIBGYOR stands for the seven color of the spectrum of white light where V stands for Violet, I for Indigo, B for Blue, G for Green, Y for Yellow, O for Orange and R for Red.

8. In the formation of spectrum of white light by a prism :
(i) which colour is deviated least?
(ii) which colour is deviated most?

Answer

→ (i) Red color is least deviated.
(ii) Violet color is most deviated color.

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

Answer

→ On the two sides of the 'green color' in the spectrum of white light are Yellow and Blue.

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

Answer

→ Newton was the scientist who discovered that sunlight consists of seven colors.

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

Answer

→ Red, Orange, Yellow, Green, Blue, Indigo and Violet this is the order of color in a rainbow, from the outside to the world.

12. Which colour of the spectrum has
(a) longest wavelength, and
(b) shortest wavelength ?

Answer

→ (a) Red has longest wavelength.
(b) Violet has the shortest wavelength.

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

Answer

→ Red light has the longer wavelength.

14. Which colour of light has the shorter wavelength - red or violet ?

Answer

→ Violet has the shortest wavelength.

15. Fill in the blanks with suitable words:
(a) When a ray of light enters a prism, it bends.................the normal; as it leaves the prism, it bends ............ the normal.
(b) White light is composed of .............colours. The colour of white light deviated through the largest angle by a prism is..............

Answer

→ (a) When a ray of light enters a prism, it bends towards the normal; as it leaves the prism, it bends away from the normal.
(b) White light is composed of seven colors. The color of white light deviated through the largest angle by a prism is violet.

Short Answer Type Questions-Pg-288

16A. 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.

Answer



16B. Mark the least deviated colour in your diagram.

Answer



16C. Why do different coloured rays deviate differently in a prism?

Answer

→ Different color have different speed of travelling so different color deviates differently in prism.

17A. What happens when a ray of ordinary light is passed through a triangular glass prism?

Answer

→ A band of seven colors appears when a ray of ordinary light is passed through a triangular glass prism.

17B. What will happen if another similar glass prism is placed upside down behind the first prism?

Answer

→ When another similar glass prism is placed upside down behind the first prism, then the seven colored rays from the first prism which are incident on the second prism recombine to form the original white beam.

18. 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.

Answer

→ Yes, it is possible to recombine the lights of seven colours to obtain the white light again, and this can be done by placing another similar prism alongside the first prism used but it should be in inverted position. The positions of both prisms are shown bellow.

When the beam of white light enters the prism 1 then it gets dispersed in to seven colors, the prism 2 which is kept alongside the prism 1 but in inverted direction receives the all seven colors then the prism 2 recombines the all colors to form a single white light. This is due to the refraction produced by the second prism is equal and opposite to that of the refraction produced by the first prism.

19A. What is spectrum? What is the name of glass shape used to produce a spectrum?

Answer

→ When a beam of white light is passed through a glass prism, and a band of seven colors formed on a white screen then this phenomenon is termed as spectrum. The name of glass shape used to produce a spectrum is prism.

19B. How many colours are there in a full spectrum of white light? Write the various colours of spectrum in the order, starting with red.

Answer

→ In a full spectrum of white light there are seven colors. The colors are Red, Orange, Yellow, Green, Blue, Indigo and Violet.

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

Answer

→ When the white light splits into seven color on passing through a transparent medium like a glass prism is called dispersion of light.
The formation of a rainbow can be shown in the fig. given bellow:-

Like the prism acts the rainbow. During the rain when sunlight enters and leaves these raindrops, the various colored rays in white light are refracted by different amounts due to which an arc of seven colors called rainbow is formed.

21. 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.

(a) State the colour seen (i) at X, and (ii) at Y.
(b) Why do different colours of white light bend through different angles with respect to the incident beam of light?

Answer

→ (a) i) The color seen at X is violet. ii) the color seen at Y is red.
(b) Different colors of white light bend through different angles with respect to the incident beam of light because every color have their own wave length, so they bend at different angles.

22. 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.

Answer

→ A diagram to show how white light can be dispersed into a spectrum by using a glass prism can be shown as:-


23. Make two diagrams to explain refraction and dispersion.

Answer

→ Refraction can be shown like :-

Dispersion can be shown by :-


24. Describe how you could demonstrate that white light is composed of a number of colors.Solutions of The Human Eye and The Colourful World Lakhmir Singh Manjit Kaur VSAQ, and SAQ Pg No. 115 Class 10 Physics

Answer

→ When we allow a white light’s beam to pass through a glass prism, then the white light splits to form a band of seven color. This shows that white light is composed of seven colors.

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

Answer

→ When the colors of a spectrum from one prism are allowed to fall on a similar prism placed adjacent to the first prism, but in inverted position. Then the refraction produced by second prism is equal and opposite to that produced by the first prism. Which makes the colors of the spectrum combine to give white light.

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

Answer

→ Violet light is refracted most by a prism. This is because violet colored light has the least speed in glass prism.

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