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प्रश्न
What is myopia?
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उत्तर
Myopia (or) short-sightedness is a vision defect in which a person can see nearby objects clearly but cannot see the distant objects clearly beyond a certain point.
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संबंधित प्रश्न
Answer the following question in detail.
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Discuss about astronomical telescope.
The near point and the far point for a person are 50 cm and 500 cm, respectively. Calculate the power of the lens the person should wear to read a book held in hand at 25 cm. What maximum distance is clearly visible for the person with this lens on the eye?
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 ____________.
If astronomical telescope of length 1.53 m has magnifying power of magnitude 50, the values of fo and fe are ____________.
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 magnifying power of a telescope is high if its objective and eyepiece have 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.
In the adjoining figure, AB represents the incident ray, and BK is the reflected ray. If angle BCF = θ, then ∠BFP is given by ______.
A camera objective has an aperture diameter of d. If the aperture is reduced to diameter d/2, the exposure time under identical conditions of light should be made ______.
