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प्रश्न
Name the physical quantity whose unit is dioptre.
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उत्तर
The power of a lens is a physical quantity with dioptre as it's unit.
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संबंधित प्रश्न
A student uses a lens of focal length 40 cm and another of –20 cm. Write the nature and power of each lens
The lens A has a focal length of 25 cm whereas another lens B has a focal length of 60 cm. Giving reason state, which lens has more power: A or B.
Which of the two has a greater power: a lens of short focal length or a lens of large 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?
An object of height 4 cm is placed at a distance of 15 cm in front of a concave lens of power, −10 dioptres. Find the size of the image.
A convex lens of power 5 D and a concave lens of power 7.5 D are placed in contact with each other. What is the :
(a) power of this combination of lenses?
(b) focal length of this combination of lenses?
A converging lens has a focal length of 50 cm. The power of this lens is:
The power of a lens is + 1.0 D is :
How does focal length of a lens change when red light incident on it is replaced by violet light? Give reason for your answer.
Define power of a lens. Write its units. Deduce the relation `1/f =1/f_1 +1/f_2`for two thin lenses kept in contact coaxially.
A double convex lens has two surfaces of equal radii R and refractive index \[m = 1 \cdot 5\]
A screen is placed a distance 40 cm away from an illuminated object. A converging lens is placed between the source and the screen and its is attempted to form the image of the source on the screen. If no position could be found, the focal length of the lens
A double convex lens has focal length 25 cm. The radius of curvature of one of the surfaces is double of the other. Find the radii, if the refractive index of the material of the lens is 1.5.
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.
The power of lens depends on the focal length of the lens
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 double convex lens is equal to the radius of curvature of either surface. What is the refractive index of its material?
In what unit is the power of a lens expressed?
