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What is presbyopia? - Science

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प्रश्न

What is presbyopia?

लघु उत्तरीय
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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).

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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.

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Optical Instruments
  क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
अध्याय 7: Wave Optics - Evaluation [पृष्ठ १०४]

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सामाचीर कलवी Physics - Volume 1 and 2 [English] Class 12 TN Board
अध्याय 7 Wave Optics
Evaluation | Q 48. | पृष्ठ १०४

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 a terrestrial telescope and an astronomical telescope?


Answer the following question in detail.

Obtain the expressions for magnifying power and the length of an astronomical telescope under normal adjustments.


Discuss about simple microscope and obtain the equations for magnification for near point focusing and normal focusing.


What is the near point focusing?


What is myopia?


Obtain the equation for resolving the power of the microscope.


Explain the experimental determination of the material of the prism using a 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 light wave of wavelength λ is incident on a slit of width d. The resulting diffraction pattern is observed on a screen at a distance D. If linear width of the principal maxima is equal to the width of the slit, then the distance D is


There are four convex lenses L1, L2, L3 and L4 of focal length 2, 4, 6 and 8 cm, respectively. Two of these lenses from a telescope of length 10 cm and magnifying power 4. The objective and eye lenses are respectively


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.


The speed of light in media 'A' and 'B' are 2.0 × 1010 cm/s and 1.5 × 1010 cm/s respectively. A ray of light enters from medium B to A at an incident angle 'θ'. If the ray suffers total internal reflection, then ______.


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 ______.


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