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प्रश्न
A student sitting in the last row of the class-room is not able to read clearly the writing on the blackboard.
How can this defect by corrected?
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उत्तर
To correct his defect, he should use concave lenses in his spectacles.
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संबंधित प्रश्न
Which defect of vision can be rectified:
by using a convex lens?
What is the other name for
myopia
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?
The near-point of a person suffering from hypermetropia is at 50 cm from his eye. What is the nature and power of the lens needed to correct this defect? (Assume that the near-point of the normal eye is 25 cm).
A person having short-sight cannot see objects clearly beyond a distance of 1.5 m. What would be the nature and power of the corrective lens to restore proper vision?
The defect of vision in which the eye-lens of a person gets progressively cloudy resulting in blurred vision is called:
(a) myopia
(b) presbyopia
(c) colourblindness
(d) cataract
A person can read a book clearly only if he holds it at an arm's length from him. Name the defect of vision:
if the person is a young man
Explain the terms ‘adaptation’ and ‘accommodation’ with reference to the eye.
A person cannot read newspaper placed nearer than 50 cm from his eyes. Name the defect of vision he is suffering from. Draw a ray diagram to illustrate this defect. List its two possible causes. Draw a ray diagram to show how this defect may be corrected using a lens of appropriate focal length.
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.
Distinguish between the following pair of words:
Myopia and hypermetropia
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.
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.
|
Give Reason:
Older people require glasses to read and write.
Give Reason:
When you enter into a dark room from bright because of sunlight, you can not see things for a few seconds.
What type of lens is used to correct Hypermetropia?
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.
Mention, if the following statement is True or False
Hypermetropia is a defect of the eye caused due to the eyeball elongation
Myopia may arise due to ____________.
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.
