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प्रश्न
Due to elongation of _______ and increase in curvature of the eye lens, a person cannot see distant objects clearly.
विकल्प
eyeball
pupil
eyelid
cornea
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उत्तर
Due to elongation of eyeball and increase in curvature of the eye lens, a person cannot see distant objects clearly.
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संबंधित प्रश्न
Write the importance of ciliary muscles in the human eye. Name the defect of vision that arises due to gradual weakening of the ciliary muscles. What types of lenses are required by the person suffering from this defect to see the objects clearly?
Akshay, sitting in the last row in his class, could not see clearly the words write on the blackboard. When the teacher noticed it, he announced if any student sitting in the front row could volunteer to exchange his seat with Akshay. Salman immediately agreed to exchange his seat with Akshay. He could now see the words written on the blackboard clearly. The teacher thought it fit to send the message to Akshay’s parents advising them to get his eyesight checked.
In the context of the above event, answer the following questions:-
(a) Which defect of vision is Akshay suffering from? Which type of lens is used to correct this defect?
(b) State the values displayed by the teacher and Salman.
(c) In your opinion, in what way can Akshay express his gratitude towards the teacher and Salman?
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.
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 concave lens?
Which defect of vision can be rectified:
by using a convex lens?
Name the defect of vision in which the eye-lens loses its power of accommodation due to old age.
What is the far point of a person suffering from myopia (or short-sightedness)?
Where is the near point of a person suffering from hypermetropia (or long-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?
- What type of lenses-converging or diverging-would an optician prescribe for her?
A person suffering from the eye-defect myopia (short-sightedness) can see clearly only up to a distance of 2 metres. What is the nature and power of lens required to rectify this defect?
Though a woman can see the distant object clearly, she cannot see the nearby objects clearly. She is suffering from the defect of vision called:
(a) long-sight
(b) short-sight
(c) hind-sight
(d) mid-sight
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?
To read a book held at a distance of 25 cm, will she need converging or diverging spectacle lenses?
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.
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.
Draw a ray diagram to show how Hypermetropia is defect can be corrected using a lens.
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?
Name the following:
The photosensitive pigment present in the rod cells of the retina.
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.
Choose the correct answer :
Presbyopia is a disease of _____________
Name an old age eye defect. Why is it caused?
Give Reason:
Why do we see clearly in the central region of the retina?
Give Reason:
Older people require glasses to read and write.
Give Reason:
Deficiency of vitamin A causes night blindness.
Explain the Term: Cataract
What type of lens is used to correct Astigmatism?
What type of lens is used to correct Hypermetropia?
The diagram given below represents the cross-section of the human eye:
(i) Name the parts labeled 1—12.
(ii) What is the function of the part marked ‘10’?
(iii) What would happen if part ‘5’ is damaged or cut?
With respect to human eye explain:
(i) How is the image formed on the retina?
(ii) How is the amount of light entering the eye-controlled?
(iii) What type of lens is used for the correction of ‘Long sight’ defect?
(iv) With the help of a ray, diagram show the defect of the eye and then its correction after the use of a lens.
Write scientific reason.
Nearsightedness, this defect can be corrected by using spectacles with concave lens.
Given below is a diagram showing a defect of vision. Name the defect of vision and draw an accurately labelled diagram to correct this defect.
Assertion: Myopia is the defect of vision in which a person cannot see distant objects clearly.
Reason: This due to eye-ball being too short.
Draw ray diagram showing myopic eye.
A student sitting at the back of the classroom cannot read clearly the letters written on the blackboard. What advice will a doctor give to her? Draw ray diagram for the correction of this defect.
Observe the figure whether it is correct or not and explain the phenomenon.
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.
