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प्रश्न
If the lens is of focal length 25 cm. Calculate the power of the lens.
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उत्तर
Focal length = 25 cm = 0.25 m
P = `1/0.25` = 4D
संबंधित प्रश्न
Define 1 dioptre of power of a lens.
What is the focal length of a convex lens of focal length 30 cm in contact with a concave lens of focal length 20 cm? Is the system a converging or a diverging lens? Ignore thickness of the lenses.
Name the physical quantity whose unit is dioptre.
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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A normal eye is not able to see objects closer than 25 cm because
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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.
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.
Power of a lens is – 4D, then its focal length is
