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प्रश्न
Differentiate between:
Short-sightedness and Long-sightedness.
उत्तर
| Short-Sightedness | Long-Sightedness |
| (i) The inability of the eye lens to focus images of distant objects on the retina; so the images fall in front of the retina. | The inability of the eye lens to focus near object images on the retina; so the images fall beyond the retina. |
| (ii) It is corrected by using glasses of a concave lens. | It is corrected by using glasses of a convex lenses. |
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संबंधित प्रश्न
What is the far point and near point of the human eye with normal vision?
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?
What is the other name for
myopia
A man can read the number of a distant but clearly but he finds difficulty in reading a book.
From which defect of the eye is he suffering?
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?
What is short-sightedness? State the two causes of short-sightedness (or myopia). With the help of ray diagrams, show:
(i) the eye-defect short-sightedness.
(ii) correction of short-sightedness by using a lens.
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
Name the following:
The photosensitive pigment present in the rods of the retina.
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.
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.
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.
Give Reason:
Deficiency of vitamin A causes night blindness.
Draw a neat labeled diagram to show how hypermetropia can be rectified.
What type of lens is used to correct Hypermetropia?
Assertion: Concave mirrors are used as reflectors in torches, vehicle head lights and in search lights.
Reason: When an object is placed beyond the center of curvature of a concave mirror, the image formed is real and inverted.
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.
A teacher drew the diagram of the heart on the blackboard and told the students to copy it in their notebooks. Mahesh couldn't see the diagram clearly as it appeared blurred to him.
- Name the defect of the eye Mahesh is suffering from.
- Where is the image formed in this defect?
- Mahesh consults an eye doctor and is prescribed suitable lenses to correct the defect. Which type of lens do his spectacles have?
