Explan the correction of the eye defect Hypermetropia.

1.	Explan the correction of the eye defect Hypermetropia.
Answer» Solution :1) A person with hypermetropia can see distant objcts clearly but cannot see objects at near distances. This is also known as 'Far sightedness'. 2) EYE lens can be form a clear image on the retina when any object is placed beyond near point. 3) To CORRECT the defect of hypermetropia , we need to use a lens which FORMS an image of an object beyond near point at H. When the object is between H and L. This is posible only when a double convex lens is used. 4) The image acts like an object for the eye lens. HENCE final image due to eye is formed at retina. Here object distance (u)=-25 CM Image distance(v) = distance of near point =-d f is the focal length of bi-convex lens. We known, `(1)/(f)=(1)/(v)-(1)/(u)implies(1)/(f) = (1)/(-d)-(1)/(-25)implies(1)/(f)=(1)/(-d)+(1)/(25)implies(1)/(f)=(d-25)/(25d)` 5) If d `gt` 25, then f becomes positive, it indicates that we need to used biconvex lens.

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