25.16.Set Up:From the shape of the cornea shown in the figure,and Solve:and The power is and the lens is diverging.25.17.Set Up:From Table 25.1, the near point is 10 cm.Solve:For For Reflect:The eye changes the focal length of its lens by using muscles to change the shape of the lens.25.18.Set Up:From Table 25.1, the near point is 22 cm. Solve: (a)The power is(b)so the image isinverted. so the image is real.(c)25.19.Set Up:For a double convex lens,and To compute in diopters,and must be expressed in meters. Maximum power corresponds to minimum focal length.(a)maximum power:minimum power:(b)(c)For a distant object and At maximum power,so (d)At minimum power,soReflect:Since the distance from the lens to the retina is fixed, this eye won’t focus clearly on both objects.25.20.Set Up:For an object 25.0 cm from the eye, the corrective lens forms a virtual image at the near point ofthe eye.Solve: (a)The person is farsighted.(b)A converging lens is needed.(c)The power is 10.562 m5 11.78 diopters.f5ssrs1sr5125.0 cm21245.0 cm225.0 cm245.0 cm5 156.2 cm.1s11sr51f.sr5sfs2f5125 cm210.667 cm225 cm20.667 cm50.685 cm56.85 mm.1s11sr5
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Corrective lens, Dioptre, 1 25.0 cm, 2 0.667 cm