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प्रश्न
Rewrite the following table so as to match second and third column with first column.
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Column I
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Column II
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Column III
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(i) Myopia
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Old age problem
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Bifocal lens
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(ii) Presbyopia
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Nearsightedness
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Concave lens.
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उत्तर
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Column I
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Column II
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Column III
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(i) Myopia
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Nearsightedness
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Concave lens.
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(ii) Presbyopia
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Old age problem
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Bifocal lens
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APPEARS IN
संबंधित प्रश्न
In a Std. X class out of 40 students 10 students use spectacles, 2 students have positive power and 8 students have negative power of lenses in their spectacles.
Answer the following questions:
(1) What does the negative power indicate?
(2) What does the positive power indicate?
(3) Generally which type of spectacles do most of the students use?
(4) What defect of eyesight do most of the students suffer from?
(5) Give two possible reasons for the above defect.
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.
Explain two possible reasons of myopia. How can it be corrected? Explain with a suitable diagram.
the biological/technical terms for the lens of eye losing flexibility resulting in a kind of long-sightedness in middle aged people.
A student is unable to see clearly the words written on the black board placed at a distance of approximately 3 m from him. Name the defect of vision the boy is suffering from. State the possible causes of this defect and explain the method of correcting it.
Name the defect of vision in a person:
whose near point is more than 25 on away.
What is the other name for
myopia
Name the defect of vision which makes the eye-lens cloudy resulting in blurred vision.
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.
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.
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.
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
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?
Name an old age eye defect. What happens in it?
An old man cannot see objects closer than 1 m from the eye clearly. Name the defect of vision he is suffering from. How can it be corrected? Draw ray diagram for the (i) defect of vision and also (ii) for its correction.
List two causes of presbyopia. Draw labelled diagram of a lens used for the correction of this defect of vision.
Name the following:
The photosensitive pigment present in the rod cells of the retina.
Given below is a diagram depicting a defect of the human eye? Study the same and answer the question that follow :
Name the type of lens used to correct this eye defect.
Given below is a diagram depicting a defect of the human eye? Study the same and answer the question that follow:
Draw a labeled diagram to show how the above mentioned defect is rectified using the lens named above.
Have a look at the posture of this woman who is reading a book and answer the questions which follow:
What are the two conditions shown in sections A and B of the eye as applicable to her?
Have a look at the posture of this woman who is reading a book and answer the questions which follow:
What kind of looking glasses she needs?
Anuja cannot see the blackboard writing but she can see nearby things.
(a) What is the eye defect she is suffering from?
(b) State the possible reason for her defect.
(c) How is it corrected
In what two whys is a yellow spot different from the blind spot?
Give Reason:
Why do we see clearly in the central region of the retina?
Give Reason:
When you enter into a dark room from bright because of sunlight, you can not see things for a few seconds.
Draw a neat labeled diagram to show how hypermetropia can be rectified.
Explain the Term: Hypermetropia
The diagram given below represents the cross-section of the human eye:
(i) Name the parts labeled 1—12.
(ii) What is the function of the part marked ‘10’?
(iii) What would happen if part ‘5’ is damaged or cut?
Choose the Odd One Out:
In Myopia the human eye _______.
Observe the given below the figure, correct it and explain and write about the concept depicted in this figure.
What are the causes of ‘Myopia’?
Differentiate the eye defects: Myopia and Hypermetropia
Myopia and hypermetropia can be corrected by:
Assertion: Myopia is the defect of vision in which a person cannot see distant objects clearly.
Reason: This due to eye-ball being too short.
Draw ray diagram showing myopic eye.
Correlate the given sequence:
Hypermetropia : Convex lens : ______ : Concave lens
