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प्रश्न
What is presbyopia?
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उत्तर १
This defect is similar to hypermetropia i.e., a person having this defect cannot see nearby objects distinctly, but can see distant objects without any difficulty. This defect occurs in elderly persons (aged persons).
उत्तर २
Presbyopia is a vision disorder that develops with age, usually beyond 40. This condition causes a progressive loss of visual focus on close objects.
संबंधित प्रश्न
Answer the following question in detail.
How does magnifying power differ from linear or lateral magnification?
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Derive an expression for the magnifying power of a simple microscope. Obtain its minimum and maximum values in terms of its focal length.
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Obtain the expressions for magnifying power and the length of an astronomical telescope under normal adjustments.
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What is the limitation in increasing the magnifying powers of a simple microscope?
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What is the limitation in increasing the magnifying powers of a compound microscope?
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What is the limitation in increasing the magnifying powers of the astronomical telescope?
What is myopia?
What is the remedy of myopia?
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What is the remedy of hypermetropia?
What is astigmatism? What is its remedy?
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Mention different parts of the spectrometer.
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The magnifying power of a telescope is nine. When it is adjusted for parallel rays, the distance between the objective and eyepiece is 20 cm. The focal length of objective and eyepiece are respectively.
A simple microscope is used to see the object first in blue light and then in red light. Due to the change from blue to red light, what is the effect on its magnifying power?
Magnification produced by astronomical telescope for normal adjustment is 10 and length of telescope is 1.1 m. The magnification when the image is formed at least distance of distinct vision (D = 25 cm) is ______.
In the adjoining figure, AB represents the incident ray, and BK is the reflected ray. If angle BCF = θ, then ∠BFP is given by ______.
