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प्रश्न
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?
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उत्तर
- Myopia : When a person can see nearby objects clearly but cannot see distant objects distinctly then the person is suffering from myopia. A person with this defect has the far point nearer than infinity. Myopia is also known as near-sightedness.
Myopia eye - Correction of Myopia : Wearing of concave lens diverges the light rays to help the image to be focused on the retina, hence myopia is corrected using the concave lens of suitable focal length.
Correction for Myopia - Hypermetropia: When a person can see distant objects clearly but cannot see nearby objects distinctly, then the person is suffering from hypermetropia. The near point, for the person, is farther away from the normal near point (25 cm). Hypermetropia is also known as far-sightedness.
Hypermetropic eye - Correction of hypermetropia : Wearing a convex lens in front of a hypermetropic eye converges the light rays to help the image to be focused on the retina, hence this defect is corrected using the convex lens of suitable focal length.
Correction of hypermetropia eye
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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.
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.
Name the defect of vision in a person:
whose near point is more than 25 on away.
Name the defect of vision in a person:
whose far point is less than infinity
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.
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?
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
Which part of the eye is grafted in a needy patient from a donated eye?
A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from? How can it be corrected?
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?
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.
Differentiate between:
Myopia and Hypermetropia.
Draw a neat labeled diagram to show how hypermetropia can be rectified.
Explain the Term: Hypermetropia
Mention, if the following statement is True or False
Hypermetropia is a defect of the eye caused due to the eyeball elongation
Choose the Odd One Out:
Which of the following statement is correct?
Which of the following statement is correct?
Observe the following diagram and answer questions following it:
- Identify the defect of vision shown.
- List its two causes.
- Name the type of lens used for the correction of this defect.
