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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.
Define and describe the magnifying power of an optical instrument.
Answer the following question in detail.
Derive an expression for the magnifying power of a simple microscope. Obtain its minimum and maximum values in terms of its focal length.
Answer the following question in detail.
What is the limitation in increasing the magnifying powers of a simple microscope?
What is the use of an erecting lens in a terrestrial telescope?
What are the uses of spectrometer?
What is myopia?
What is the remedy of hypermetropia?
Discuss about simple microscope and obtain the equations for magnification for near point focusing and normal focusing.
Obtain the equation for resolving the power of the microscope.
Explain the preliminary adjustments of the spectrometer.
A compound microscope has a magnification of 30. The focal length of eye piece is 5 cm. Assuming the final image to be at least distance of distinct vision, find the magnification produced by the objective.
A compound microscope has a magnifying power of 100 when the image is formed at infinity. The objective has a focal length of 0.5 cm and the tube length is 6.5 cm. What is the focal length of the eyepiece.
When a convex lens of 12.5 cm focal length is used as a magnifying glass, normal eye can see an object clearly at a distance of 25 cm. The magnifying power of the instrument is ____________.
The magnifying power of a telescope is high if its objective and eyepiece have 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?
An object viewed from a near point distance of 25 cm, using a microscopic lens with magnification '6', gives an unresolved image. A resolved image is observed at infinite distance with a total magnification double the earlier using an eyepiece along with the given lens and a tube of length 0.6 m, if the focal length of the eyepiece is equal to ______ cm.
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 ______.
The image formed by an objective of a compound microscope 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 ______.
