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प्रश्न
Give the usual name for the following:
A point inside a lens through which the light passes undeviated.
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उत्तर
The usual name for a point inside a lens through which light passes undeviated is the optical center
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संबंधित प्रश्न
Define 1 dioptre of power of a lens.
Find the focal length of a lens of power −2.0 D. What type of lens is this?
Kavita from 10th is using spectacles. The power of the lenses in her spectacles is –2.5 dioptre. Answer the following questions:
1) Which lenses are used in her spectacles?
2) State the defect of vision Kavita is suffering from.
3) Find the focal length of the lenses used in her spectacles
What can you see in a completely dark room? If you switch on an electric bulb in this dark room as a light source, explain how you could now see:
(a) the electric bulb
(b) a piece of white paper
How is the power of a lens related to its focal length?
The power of a lens is, −2 D. What is its focal length?
The optician's prescription for a spectacle lens is marked +0.5 D. What is the:
(a) nature of spectacle lens?
(b) focal length of spectacle lens?
A lens has a focal length of, −10 cm. What is the power of the lens and what is its nature?
Define the term focal length of a lens.
State the condition for the following a lens has both its focal lengths equal .
On reducing the focal length of a lens, its power ______.
How is accommodation produced?
Which lens has more power a thick lens or a thin lens?
If focal length of a convex lens is 20 cm at what is the power of the lens?
Match the following:
| Column - I | Column - II | ||
| 1 | Retina | a | Path way of light |
| 2 | Pupil | b | Far point comes closer |
| 3 | Ciliary muscles | c | near point moves away |
| 4 | Myopia | d | Screen of the eye |
| 5 | Hypermetropia | e | Power of accommodation |
The power of convex lens of focal length 20 cm is ______.
The deviation of the incident light rays produced by a lens on refraction through it is a measure of its:
A negative power of a lens indicates a:
If the lens material and the surrounding liquid have the same refractive index (\[n_2 = n_1\]), then:
