A teacher notices a child in her class holds pages 15cm from his eyes when readi

Question

A teacher notices a child in her class holds pages 15cm from his eyes when reading.

a) is the child myopic or hyperopic?

b) what kind of lens should be used to correct the child's vision, and what should its power be in diopters? (Hint: the lens needs to form a virtual image at the far point of the student, the 15cm. A normal eye has a far point for objects effectively equal to infinity. Assume the lens is 2cm from the eye.)

C) if the near point for this person is 10cm, where would the near point be for this person when wearing glasses?

Explanation / Answer

(a)   Is hyeropic ,since the child reads the book at a distance less than the normal distance what we should mantian to read the book is 25 cm.

(b)   For the hyperopic, concave lens should be taken,

powerer of the lens in diaptores is P=100/f (in meters)                                                     

f=25-(15+2)cm =8 cm,

P=100/8

=-12.5,

(c) 25-10 cm = 15 cm

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