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प्रश्न
State the condition for the following a lens has both its focal lengths equal .
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उत्तर
If a lens has both its focal length equal medium is same on either side of lens.
संबंधित प्रश्न
A doctor has prescribed a corrective lens of power +1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging?
Give the usual name for the following:
A point inside a lens through which the light passes undeviated.
A lens has a focal length of, −10 cm. What is the power of the lens and what is its nature?
An object of height 4.25 mm is placed at a distance of 10 cm from a convex lens of power +5D. Find (i) the focal length of the lens, and (ii) the size of the image.
Two lenses A and B have focal lengths of +20 cm and, −10 cm, respectively.
(a) What is the nature of lens A and lens B?
(b) What is the power of lens A and lens B?
(c) What is the power of combination if lenses A and B are held close together?
What is the unit of power of a lens? Define the unit of power of a lens.
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.
The power of a lens is +2.0 D. Find its focal length and state the kind of 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 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?
