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प्रश्न
Nearsightedness : concave lens : : farsightedness : _______
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उत्तर
Nearsightedness : concave lens : : farsightedness : convex lens
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संबंधित प्रश्न
Given below is a diagram showing a defect of human eye. Study it and answer the following questions.
(i) Name the defect shown in the figure.
(ii) Give reason for this defect of eye in human being.
(iii) Name the type of lens used to correct the eye defect.
What is myopia?
Millions of people in the developing countries of the world are suffering from corneal blindness. These persons can be cured by replacing the defective cornea with the cornea of a donated eye. A charitable society of your city has organised a campaign in your neighbourhood in order to create awareness about this fact. If you are asked to participate in this mission, how would you contribute in this noble cause?
(i) State the objective of organising such campaigns.
(ii) List two arguments which you would give to motivate the people to donate their eyes after death.
(iii) List two values which are developed in the persons who actively participate and contribute in such programmes.
What is the far point and near point of the human eye with normal vision?
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.
Which defect of vision can be rectified:
by using a concave lens?
What is the other name for
hypermetropia
Name any two defects of vision which can be corrected by using spectacles.
Name the body part with which the terms myopia and hypermetropia are connected.
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?
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?
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?
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?
Explain with the help of labelled ray-diagram, the defect of vision called hypermetropia, and hot it is corrected by a lens.
The defect of vision which cannot be corrected by using spectacles is:
(a) myopia
(b) presbyopia
(c) cataract
(d) hypermetropia
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
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
Which part of the eye is grafted in a needy patient from a donated eye?
What is meant by optical illusion? Give one example.
Explain the terms ‘adaptation’ and ‘accommodation’ with reference to the eye.
You do not enjoy watching a movie from a very short distance from the screen in a cinema hall. Why?
What eye defect is hypermetropia? Describe with a ray diagram how this defect of vision can be corrected by using an appropriate lens.
When do we consider a student sitting in the class to be myopic? List two causes of this defect. Explain using a ray diagram how this defect of eye can be corrected.
The diagram alongside represents a section of a mammalian eye.
(i) Label the parts 1 to 5 of the diagram.
(ii) State the function of the parts labelled 4 and 5.
(iii) With the help of a diagram show the short sightedness.
Choose the correct answer :
Presbyopia is a disease of _____________
Given below is a diagram depicting a defect of the human eye? Study the same and answer the question that follow:
Give two possible reasons for this defect of the eye in human beings.
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.
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?
Rewrite the following table so as to match second and third column with first column.
|
Column I
|
Column II
|
Column III
|
|
(i) Myopia
|
Old age problem
|
Bifocal lens
|
|
(ii) Presbyopia
|
Nearsightedness
|
Concave lens.
|
The near point of the eye of a person is 50 cm. Find the nature and power of the corrective lens required by the person to enable him to see clearly the objects placed at 25 cm from the eye?
A person is unable to see objects distinctly placed within 50 cm from his eyes.
(a) Name the defect of vision the person is suffering from and list its two possible causes.
(b) Draw a ray diagram to show the defect in the above case.
(c) Mention the type of lens used by him for the correction of the defect and calculate its power. Assume that the near point for the normal eye is 25 cm.
(d) Draw a labeled diagram for the correction of the defect in the above case.
Explain the Term: Astigmatism
Write scientific reason.
Nearsightedness, this defect can be corrected by using spectacles with concave lens.
Assertion: Concave mirrors are used as reflectors in torches, vehicle head lights and in search lights.
Reason: When an object is placed beyond the center of curvature of a concave mirror, the image formed is real and inverted.
Which of the following statement is correct?
Myopia may arise due to ____________.
A person needs a lens of power –4.5 D for correction of her vision.
- What kind of defect in vision is she suffering from?
- What is the focal length of the corrective lens?
- What is the nature of the corrective lens?
When do we consider a person to be myopic or hypermetropic? Explain using diagrams how the defects associated with myopic and hypermetropic eye can be corrected?
