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प्रश्न
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 ___________.
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उत्तर
The reciprocal of the focal length in metres gives you the power of the lens, which is measured in dioptres.
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संबंधित प्रश्न
What is meant by a power of a lens? Define its SI unit.
Define 1 dioptre of power of a lens.
A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? Also, find the power of the lens.
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
Consider two statements A and B given below:
A: real image is always inverted
B: virtual image is always erect
Out of these two statements:
Which type of lens has (a) a positive power, and (b) a negative power?
How is the power of a lens related to its focal length?
The focal length of a convex lens is 25 cm. What is its power?
A converging lens has focal length of 50 mm. What is the power of the lens?
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.
What is the unit of power of a lens? Define the unit of power of a lens.
A combination of lenses for a camera contains two converging lenses of focal lengths 20 cm and 40 cm and a diverging lens of focal length 50 cm. Find the power and focal length of the combination.A optical instrument in which the above arrangement of convex lens is used is a convex lens used to burn paper by focusing sunlight.
State the condition for the following a ray passes undeviated through the lens .
A double convex lens has two surfaces of equal radii R and refractive index \[m = 1 \cdot 5\]
Power of a lens is – 4D, then its focal length is
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?
