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What power of spectacle lens is needed to allow a farsighted person, whose near point is...

What power of spectacle lens is needed to allow a farsighted person, whose near point is 2.50 m, to see an object clearly that is 20.0 cm away? Assume the spectacle (corrective) lens is held 2 cm away from the eye by eyeglass frames.

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Answer #1

When the object is away from the eyes, the lens should produce image at near point . Since lens is away from the eyes at , the image will be at away from the eyes. Therefore, image distance and object distance is .

The power of lens is given by:

Therefore, lens power must be 5.1523 Dioptre for given situation.

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