HUMAN EYE AND COLOURFUL WORLD 10

PRACTICE PAPER

                     SUB:PHYSICS (2020)                   

CLASS X            HUMAN EYE AND COLOURFUL WORLD                         
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I. Very short answer type question: 

1. What is the function of aqueous humor and vitreous humor?
2. When we enter from bright sunlight to a dark room, we can not see initially. Why?
3. A person uses spectacles of power +2D. What is the defect of vision he is suffering from?
4. Why do chickens wake up early and sleep early?
5. What is the nature of the image formed at retina?
6. What is the cause of colour blindness?
7. State the structure of iris and its functions in the human eye.
8. Define the distance of distinct vision and give its range.
9. What is meant by the least distance of distinct vision? 
10. Define power of accommodation of the eye.
11. Why the clear sky appear blue?
12. Why does it take some time to see objects in a cinema hall when we just entered the hall from bright sunlight? Explain in brief.
13. How does the thickness of the eye lens change when we shift looking from a distance tree to reading a book?
14. A student sitting at the back of the classroom cannot read clearly the letters written on the blackboard. What advice will a doctor give to her? Draw a ray diagram for the correction of this defect.
15. A hyper meteoric person prefers to remove his spectacles while driving. Give reason.
16. How are we able to see nearby and also the distant objects clearly? 
17. Why do parallel rays of different colours deviate differently while passing through a glass prism?
18. Name any two phenomena associated with the formation of the rainbow.
19. Draw a ray diagram showing the dispersion through a Prism when a narrow beam of white light is incident on one of its refracting surfaces. Also, indicate the order of the colours of the spectrum obtained.
20. Define the angle of deviation.
21. List the colours into which light splits in the decreasing order of their bending on emergence from the prism.
22. A beam of white light splits when it passes through a Prism. Name this phenomenon and give its reason.
23. Why does the sun look reddish at the time of sunrise and sunset? Explain.
24. Why do different components of white light split up into a spectrum, when it passes through a triangular glass prism?
25. What is the dispersion? 
26. What happens when light is passed through a glass prism.
27. What is astigmatism? 

II. Short answer type questions: 

1. What is meant by presbyopia? Mention two causes due to which presbyopia occurs. Explain how it is corrected.
2. A person can see clearly up to 3 m. Describe the type of lens that should be used so that he can see up to 12 m clearly. 
3. A far point of a nearsighted person is 1.5m. Find the nature and power of the lens required.
4. What power of the lens will change the reading distance from 1 m to 0. 25 m?
5. A person is unable to see the object nearest 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 are required for his spectacles.
6. (a) What is meant by the least distance of distinct vision?
   (b) How does iris control the size of the pupil in bright light and dim light?
7. (a) Make a ray diagram to show how the eye defect myopia is corrected by using a suitable lens.
   (b) State three reasons due to which the side effect may be caused?
   (c) A person with myopic cannot see objects beyond a distance of 1.5 m. What is the power of the lens required to correct the problem?
8. Is the position of a star as seen by us its true position? Justify your answer.
9. Why is the colour of the clear sky blue? 
10. Why do we see a rainbow in the sky only after rainfall? 
11. (a) Draw a diagram to show the formation of an image of a distant object by a myopic eye. How can such an eye defect be rectified?
    (b) State two reasons due to which this eye defect may be caused.
12. Study the diagram given below and answer the following question. 
    (i) Name the defect of vision defeated in the diagram.
    (ii) List two causes of the defects.
    (ii)  Draw a ray diagram for the correction of the above defects using an appropriate lens.
13. (a) Define the power of a lens and write its SI unit.
    (b) A convex lens of power 4D is placed at a distance of 40 cm from a wall. At what distance from the lens should be a candle placed so that its image is formed on the wall?
14. Ravi kept a book at a distance of 10 cm from the eyes of his friend Hari.  Hari is not able to read anything written on the books. Explain why?
15. A lens of the focal length of 5.0 cm is being used by a student in the laboratory as a magnifying glass. His least distance of distinct vision is 25 cm. What magnification is the student getting?
16. The near point of a person suffering from hypermetropia is 75cm. Calculate the focal length and power of the lens required to enable him to read the newspaper which is kept at 25 cm from the eye.
17. What will be the colour of the sky be for an astronaut staying in the International Space Station orbiting the earth? Justify your answer by giving reasons.
18. Why does the sun seem to rise two minutes before the actual sunrise and sets two minutes after the actual sunset? Explain with the help of the labelled diagram.
19. Explain with the help of labeled diagram the cause of twinkling of stars.
20. (a) "Stars seem higher than they actually are"
    (b) "The sky appears dark to passengers flying at very high altitude" Justify this statement with reasons.
21. Define the angle of deviation. Why do different components of white light split up into spectrum when it passes through a triangular glass prism. Show the angle of the deviation for red colour when white light passes through a prism.
22. States the difference in colour of the sun observed during sunrise, sunset and noon. Give an explanation for each.
23. Enlist at least six phenomena observed in nature subsequent to the scattering of light.
24. What is the Tyndall effect? Give at least two illustrating the Tyndall effect.
25. Name the phenomenon associated with the following:
    (a) The sky appears blue.
    (b) Formation of a rainbow in the sky.
26. What is the difference in colours of the sun observed during sunrise and sunset and noon? Give an explanation for each?
27. A beam of white light falling on a glass prism gets split up into seven colours. A student makes the statement:
    (i) The colour at the position marked 1 and 3 are similar to the colour of turmeric and the colour of chilly powder respectively. Is the above statement correct or incorrect? Justify.
    (ii) Which two positions correspond to the colour of the solution of copper sulphate and signal used to move the vehicles?
    (iii) Light of colour of chilly powder bends the most while the light of colour of brinjal bends the least. Is the statement correct? Justify.
28. Why the power of accommodation of an eye decreases with age? Explain.
29. Draw ray diagram each show:
    (i) Myopic eye (ii) Hypermetropic eye. 
30.  What is meant by the near point and far point of an eye? State their values for the normal human eyes.
31. An old person is unable to see clearly nearby objects as well as distinct
    objects.
    (a) What defect of vision is the suffering from?
    (b) What kind of lens will be required to see clearly the nearby as well as distant objects? Give reasons.
32. How is normal eye able to see distinctly distance as well as near objects? What is the distance of distinct vision?
33. A person needs a lens of power - 4.5 Di for correction of her vision.
    (i) What kind of defect in visual is she suffering from?
    (ii) What is the focal length of the corrective lens?
    (iii) What is the nature of the corrective lens?
34. How will you use two identical prisms so that a narrow beam of white light incident on one prism emerges out of the second prism as white light? Draw the diagram.
35. Stars twinkle while the planets do not. Why?
36. During sunrise and sunset sky appears red while during the day it appears blue. Explain the natural phenomenon.
37. What is the scattering of light? Explain with the help of an example?
38.  Explain giving reasons why the sky appears blue to an observer from the surface of the earth? 

III. Long answer type questions: 

1. A student suffering from myopia is not able to see distinctly the objects placed beyond 5 m. List two possible reasons due to which this defect of vision may have arisen. With the help of ray diagrams, explain.
2. (i) why the student is unable to see distinctly the objects placed beyond 5m from his eyes.
   (ii) the type of corrective lens used to restore proper vision and how this defect is corrected by the use of this lens.
3. List the parts of the human eye that control the amount of light entering into it. Explain how they perform this function.
4. Write the function of the retina in the human eye. Do you know that corneal impairment can be cured by replacing the defective cornea with the cornea of the donated eye?  How and why should we organize groups to motivate the community members to donate their eyes after death?
5. List three common refractive defects of vision. Suggest the way of correcting these defects. 
6. About 45 lakh people in the developing countries are suffering from corneal blindness about 3 lakh children below the age of 12 suffering from this defect can be cured by replacing the defective, with the cornea of a donated eye. How and why can a student of your age involve themselves to create awareness about this fact among people?
7.  A person cannot read a newspaper place near 50 cm from his eye. Name the defect of vision he is suffering from? Draw a ray diagram to illustrate the defects. List two possible causes. Draw a ray diagram to show how this defect may be corrected using a lens of appropriate focal length. We see an advertisement for eye donation on television or a newspaper. Write the importance of such an advertisement.
8. (a) What type of spectacles should be worn by a person having the defect of myopia as well as hypermetropia?
   (b) The far point of a myopic person is 150 cm. What are the nature and the power of the lens required to correct the defect?
   (c)  With the help of a ray, a diagram showing the formation of image by:
   (i) a myopic eye
   (ii) Correction of myopia by using an appropriate lens.
9.  A person's image when seen through a stream of hot air rising above a fire disappeared to waver. Explain.
10. (a) Name the defect of vision in which the eye loses its power of accommodation due to old age.
    (b) The near point of a person suffering from hypermetropia is 50 cm from his eye. What is the power of the lens needed to correct this defect?  N( near point for normal eye 25cm)
    (c) With the help of a ray diagram, show the formation of image by:
    (i) a hypermetropic eye
    (ii)  correction of hypermetropia by using an appropriate lens.
11. (a) Describe an activity along with a level diagram of the phenomenon of dispersion through a Prism.
    (b) Explain in brief the formation of the rainbow with the help of a figure.
12. State the reasons which lead to hypermetropia. With the help of a suitable diagram explain this defect of vision and its correction. Draw diagram of an experimental arrangement of observing scattering of light in Colloidal solution. Name the two chemicals used in this activity.
13.  Define dispersion. How does a prism disappear white light? Which colour of light bends the most and the least? A narrow beam of white light is passing through a glass prism. Trace it on your answer sheet and show the path of the emergent beam as observed on the screen.
14. (a) Write the name and the cause of the phenomenon observed.
    (b) Where else in nature in this phenomenon observed.
    (c) Base on the observation, state the conclusions which can be drawn about the constitution of white light.
    
15. State the natural phenomenon behind the formation of the rainbow? Explain the phenomenon. Name a device that can be used to observe such a phenomenon in the laboratory? If you are facing a rainbow in the sky, what is the position of the sun with respect to your position?

                                                  

Chapter 1 - Chemical Reactions and  Equations	Quick View	Questions with Solutions
Chapter 2 - Acid, Bases and Salt	Quick View	Questions with Solutions
Chapter 3 - Metal and Non-metals	Quick View	Questions with Solutions
Chapter 4 - Carbon and it's compound	Quick View	Questions with Solutions
Chapter 5 - Periodic Classification of Elements	Quick View	Questions with Solutions
Chapter 6 - Life Processes	Quick View	Questions with Solutions
Chapter 7 - Control and Co-ordination	Quick View	Questions with Solutions
Chapter 8 - How do Organisms Reproduce?	Quick View	Questions with Solutions
Chapter 9 -  Health and Heredity	Quick View
Chapter 10 -  Reflection and Refraction	Quick View	Questions with Solutions
Chapter 11 -  Human Eye Colourful World	Quick View	Questions with Solutions
Chapter 12 -  Electricity	Quick View	Questions with Solutions
Chapter 13 -  Magnetic Effect of Electric Current	Quick View	Questions with Solutions
Chapter 14 -  Sources of Energy	Quick View
Chapter 15  - Our Environment	Quick View
Chapter 16 - Management of  Natural  Resources	Quick View