Advertisements
Advertisements
Question
Study the following diagram carefully and then answer the questions that follow. The diagram is depicting a defect of the human eye :

(i) Identify the defect shown in the diagram.
(ii) Give two possible reasons for the above defect.
Advertisements
Solution
(i) Farsightedness or hypermetropia.
(ii)
(a) The lens is flattened or less convex,
(b) Eyeball is short.
APPEARS IN
RELATED QUESTIONS
Name the defect of vision in a person:
whose far point is less than infinity
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?

The picture given here shows a person wearing ‘half-moon’ spectacles. What sort of eye-defect do you think he has? Why are these particular spectacles useful to him?
Name an old age eye defect. What happens in it?
List two causes of presbyopia. Draw labelled diagram of a lens used for the correction of this defect of vision.
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.
|
Nearsightedness : concave lens : : farsightedness : _______
What are the causes of ‘Myopia’?
Differentiate the eye defects: Myopia and Hypermetropia
A person cannot see distinctly objects kept beyond 2 m. This defect can be corrected by using a lens of power:
