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प्रश्न
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?
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उत्तर
An optician would prescribe diverging lenses to correct her defect.
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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.
the biological/technical terms for the lens of eye losing flexibility resulting in a kind of long-sightedness in middle aged people.
What is the scientific name of
short-sightedness
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?
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?
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 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?
Name the following:
The eye defect caused due to shortening of the eye ball from front to back.
By closing the eyes and gently pressing them by your palms, you may see some specks of brilliant light. How do you get this sensation while there is no light entering your eyes?
Observer the following diagram and answer the questions.
a) Which eye defect is shown in this diagram?
b) What are the possible reasons for this eye defect?
c) How this defect is corrected, write it in brief?
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.
Given alongside is a diagram depicting a defect of the human eye. Study the same and then answer the questions that follow:
(i) Identify the defect.
(ii) Name the parts labelled 1, 2 and 3.
(iii) Give labelled two possible reasons for this eye defect.
(iv) Draw a labelled diagram to show how the above mentioned defect is rectified.
In what two whys is a yellow spot different from the blind spot?
Give Reason:
Older people require glasses to read and write.
Given below is a diagrammatic representation of a defect of the human eye:
(i) Identify the defect.
(ii) Mention two reasons for the above defect.
(iii) State how the defect can be rectified.
(iv) Name the part of the eye responsible for maintaining the shape of the eyeball.
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?
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.
Complete the following table by observing the given figures:
| Figure → |  |
 |
| Points ↓ | ||
| (a) Name of the defect | ______ | ______ |
| (b) Position of the image | ______ | ______ |
| (c) Lens used to correct the defect | ______ | ______ |
Name the following:
Two kinds of accomodations.
