In a mildly hyperopic eye, the focal length of the eye\'s natural lens can be co

Question

In a mildly hyperopic eye, the focal length of the eye's natural lens can be corrected by:

A. Contracting the ciliary muscle and increasing the radius of curvature.

B. Contracting the ciliary muscle and decreasing the radius of curvature

C. Relaxing the ciliary muscle and increasing the radius of curvature

D. Relaxing the ciliary muscle and decreasing the radius of curvature.

2. John must wear a contact lens with a power of +3.00 diopters in one eye to be able to focus on on object 25 cm in front of the eye. Based on the vision in this eye which of the following is most likely age range of John?

A. Less than 40 years old

B. 40-49

C.50-59

D.60 or older

Please show all your calculations.

Explanation / Answer

1.) In case of farsightedness the image appears to be focussed behind retina. In order bring image forward, the lens has to increase its converging power. So, we need to decreases the focal length. For that we need to relax the ciliary muscle increases the radius of curvature. Hence, c is correct answer.

2.)

Power is the reciprocal of the focal length measured in meters. Since the power is positive, Jane is farsighted.

Since P = 3.00 diopters, the focal length of the corrective lens is f = 0.33 m = 33 cm. A corrective lenscreates a virtual image, therefore, 1/i is negative.The object distance is 25 cm.

The lens distance equation rearranges to:

1/i = 1/o

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