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Question
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?
Solution
Looking glasses with the concave lens are required here.
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RELATED QUESTIONS
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.
Which defect of vision can be rectified:
by using a concave lens?
What is the scientific name of
long-sightedness?
Name the defect of vision in which the eye-lens loses its power of accommodation due to old age.
Name the defect of vision which makes the eye-lens cloudy resulting in blurred vision.
A man can read the number of a distant but clearly but he finds difficulty in reading a book.
From which defect of the eye is he suffering?
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?
Name the following:
The photosensitive pigment present in the rods of the retina.
A person is unable to see distinctly the objects closer than 1 m. Name the defect of vision he is suffering from. Draw ray diagrams to illustrate the cause of the defect and its correction by suitable lens.
Name the following:
The photosensitive pigment present in the rod cells of the retina.
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.
Solve the following question:
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?
Name an old age eye defect. Why is it caused?
Explain the Term: Astigmatism
Give Technical Term:
The path which responsible for protecting the eye from sweat.
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Due to elongation of _______ and increase in curvature of the eye lens, a person cannot see distant objects clearly.
What are the causes of ‘Myopia’?
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?
