For a myopic (short-sighted) eye, rays from far distant objects are brought to focus at a point

Assertion : Concave lens is used to correct myopia or short-sightedness. Reason : A concave lens of suitable focal length diverges the parallel rays from the distant objects as if they are coming from the far point of the myopic eye. This helps the eye lens to form a clear image at the retina.

The far point of a myopic (short-sighted ) person is 80 cm in front of the eye. What is the power of the lens required to enable him to see very distant objects clearly.

Statement I : A myopic person is advised to use concave lens. Statement II : The eye lens of a myopic person focuses the parallel rays coming from distant ogject in from distant objects in front of the retina.

After reflection, the light rays from a point object at the focus of a concave mirror,

In the eye of myopic person, the image of a distant object is formed behind the retina.

How does the eye change in order to focus on near or distant objects ?

(a) What is long-sightedness ? State the two causes of long-sightedness (or hypermetropia). With the help of ray diagrams, show : (i) the ray-defect long-sightedness. (ii) correction of long-sightedness by using a lens. (b) What eye has a near point distance of 0.75 m. What sort of lens in spectacles would be needed to reduce the near point distance to 0.25 m ? Also calculate the power of lens required. Is this eye long-sighted or short-sighted ? An eye has a far point of 2 m. What type of lens in spectacles would be needed to increase the far point to infinity ? Also calculate the power of lens required. Is this eye long-sighted or short-sighted ?