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प्रश्न
Define the power of a lens.
Define the term power of a lens.
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उत्तर १
Power of a lens is defined as the ability of a lens to bend the rays of light. It is given by the reciprocal of focal length in metre.
उत्तर २
The power of a lens is a measure of the deviation produced by it in the path of rays refracted through it.
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संबंधित प्रश्न
How is the power of a lens related to its focal length?
Which has more power : a thick convex lens or a thin convex lens, made of the same glass? Give reason for your choice.
What is the nature of a lens having a power of + 0.5 D?
What is the nature of a lens whose power is, −4 D?
Fill in the following blank with suitable words :
The reciprocal of the focal length in metres gives you the _________ of the lens, which is measured in ___________.
Fill in the following blank with suitable word:
For converging lenses, the power is __________ while for diverging lenses, the power is ___________.
The power of a combination of two lenses X and Y is 5 D. If the focal length of lens X be 15 cm :
(a) calculate the focal length of lens Y.
(b) state the nature of lens Y.
A converging lens has a focal length of 50 cm. The power of this lens is:
Find the radius of curvature of the convex surface of a plano-convex lens, whose focal length is 0.3 m and the refractive index of the material of the lens is 1.5.
A symmetric double convex lens is cut in two equal parts by a plane containing the principal axis. If the power of the original lens was 4 D, the power of a divided lens will be
Surabhi from std. X uses spectacle. The power of the lenses in her spectacle is 0.5 D.
Answer the following questions from the given information:
- Identify the type of lenses used in her spectacle.
- Identify the defect of vision Surabhi is suffering from.
- Find the focal length of the lenses used in her spectacle.
Which lens has more power a thick lens or a thin lens?
If the lens is of focal length 25 cm. Calculate the power of the lens.
The power of lens depends on the focal length 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 |
Define power of a lens. What is its unit? One student uses a lens of focal length 50 cm and another of –50 cm. What is the nature of the lens and its power used by each of them?
The focal length of a concave lens is 20 cm. The focal length of a convex lens is 25 cm. These two are placed in contact with each other. What is the power of the combination? Is it diverging, converging or undeviating in nature?
The deviation of the incident light rays produced by a lens on refraction through it is a measure of its:
1 D is equivalent to:
A negative power of a lens indicates a:
