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प्रश्न
To read a book held at a distance of 25 cm, will she need converging or diverging spectacle lenses?
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उत्तर
To read a book held at a distance of 25 cm, the person, who is long-sighted, will need converging lenses.
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संबंधित प्रश्न
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.
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.
Name the defect of vision which makes the eye-lens cloudy resulting in blurred vision.
What is the other name of old age hypermetropia?
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 an old man
Name the following:
The photosensitive pigment present in the rods of the retina.
Describe the mechanism of focusing the image of a distant object in your eye when you raise your head after reading a book.
Given below is a diagram depicting a defect of the human eye. Study the same and answer the question that follow:
Name the defect shown in the diagram.
State one role of ciliary muscles in the human eye.
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.
Choose the correct answer :
Presbyopia is a disease of _____________
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?
Name the common defects of the eye.
Give Technical Term:
The type of lens used to correct myopia is
What type of lens is used to correct Hypermetropia?
Differentiate the eye defects: Myopia and Hypermetropia
