Advertisements
Advertisements
Question
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.
Advertisements
Solution
(i) The defect shown in the figure is hypermetropia or long-sightedness.
(ii) Two possible reasons are
a) Ciliary muscles have become weak, so the converging power of the eye lens decreases.
b) Because of shortening of the eye ball or flattening of the eye lens.
(iii) To correct the eye defect, a suitable convex lens is used.
APPEARS IN
RELATED QUESTIONS
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.
About 45 lac people in the developing countries are suffering from corneal blindness. About 30 lac children below the age of 12 years suffering from this defect can be cured by replacing the defective cornea with the cornea of a donated eye. How and why can students of your age involve themselves to create awareness about this fact among people?
The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct the problem?
Which defect of vision can be rectified:
by using a convex lens?
Name any two defects of vision which can be corrected by using spectacles.
What are the two most common defects of vision (or defects of eye)? How are they corrected?
Differentiate between myopia and hypermetropia.
What is long-sightedness? State the two causes of long-sightedness (or hypermetropia). With the help of ray diagrams, show:
(i) the eye-defect long-sightedness.
(ii) correction of long-sightedness by using a lens.
The defect of vision which cannot be corrected by using spectacles is:
(a) myopia
(b) presbyopia
(c) cataract
(d) hypermetropia
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 the following:
The eye defect caused due to shortening of the eye ball from front to back.
Explain the terms ‘adaptation’ and ‘accommodation’ with reference to the eye.
A student cannot see a chart hanging on a wall placed at a distance of 3 m from him. Name the defect of vision he is suffering from. How can it be corrected? Draw ray diagrams for the (i) defect of vision and also (ii) for its correction.
An old man cannot see objects closer than 1 m from the eye clearly. Name the defect of vision he is suffering from. How can it be corrected? Draw ray diagram for the (i) defect of vision and also (ii) for its correction.
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?
List two causes of presbyopia. Draw labelled diagram of a lens used for the correction of this defect of vision.
Distinguish between the following pair of words:
Myopia and hypermetropia
Given alongside is a diagram depicting a defect of the human eye. Study the same and then answer the questions that follow:
- Identify the defect.
- Name the parts labelled 1, 2 and 3.
- Give two possible reasons for this eye defect.
- Draw a labelled diagram to show how the above mentioned defect is rectified.
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.
Given below is a diagram depicting a defect of the human eye? Study the same and answer the question that follow:
Draw a labeled diagram to show how the above mentioned defect is rectified using the lens named above.
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?
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?
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 the common defects of the eye.
Name an old age eye defect. Why is it caused?
Explain the Term: Presbyopia
Give Technical Term:
The type of lens used to correct myopia is
Choose the Odd One Out:
In Myopia the human eye _______.
Nearsightedness : concave lens : : farsightedness : _______
Differentiate the eye defects: Myopia and Hypermetropia
Myopia and hypermetropia can be corrected by:
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?
Given alongside is a diagram depicting a defect of the human eye. Study the same and answer the questions that follow:
 |
- Name the defect shown in the diagram.
- Give two possible reasons for this defect.
- Name the parts labelled 1 to 4.
- Name the type of lens used to correct this eye defect.
- Draw a labelled diagram to show how the above mentioned defect is rectified using the lens named above.
Have a look at the posture of this girl who is reading a book and answer the questions which follow:
 |
- Name the problem she is facing.
- What are the two conditions shown in sections A and B of the eye as applicable to her.
- What kind of reading glasses does she need?
 |
 |
| A | B |
