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प्रश्न
A convex lens is of focal length 20 cm. Find its power.
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उत्तर
Given: Focal length f = 20cm = 0.2 m
Power = `1/"Focal length in m"=1/0.2` = 5D
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संबंधित प्रश्न
Define 1 dioptre of power of a 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
How is the power of a lens related to its focal length?
How is the sign (+ or -) of power of a lens related to its divergent or convergent action?
On reducing the focal length of a lens, its power ______.
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A pin of length 2.00 cm is placed perpendicular to the principal axis of a converging lens. An inverted image of size 1.00 cm is formed at a distance of 40.0 cm from the pin. Find the focal length of the lens and its distance from the pin.
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Assertion and reasoning type
- Assertion: Myopia is due to the increase in the converging power of eye lens.
- Reason: Myopia can be corrected with the help of concave lens.
