Two dots separated by 7 cm are placed on a piece of paper as shown. The on the r

Question

Two dots separated by 7 cm are placed on a piece of paper as shown. The on the right can be made to disappear to a viewer who closes their left eye and focuses on the left hand dot while holding the paper at a distance of 28 cm from the open right eye. How far apart are the optic nerve and the fovea centralis? a. 0.57 cm b. 0.15 cm c. 0.03 cm d. 0.37 cm e. 0.48 cm A person cannot focus properly on objects closer than 3 m from their eye. If we want them to be able to focus on objects up to and including 10 cm away, what focusing power lens would they need? a. 10.3 diopters b. 9.7 diopters c. 5.2 diopters d. 14.7 diopters e. 3.3 diopters

Explanation / Answer

6) Using lens formula

di = -3m

do = -0.10m

f =?

1/f = 1/di - 1/do

1/f = 1/-3 + 1/0.10

1/f = P = 9.7 D

Hence answer is B

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