The lens system consists of the cornea, which acts as a fixed lens of power 38 m–1, and a variable internal lens just behind the cornea. The maximum power of the eye is 64 m–1.
Calculate:
(i) how near an object can be placed in front of the eye and still be in focus
(ii) the maximum power of the internal lens. air normal 37° cornea 27° (15)
Light is refracted as it enters the cornea from air as shown in the diagram. Calculate the refractive index of the cornea.
(6)
Draw a diagram to show the path of a ray of light as it passes from water of refractive index 1.33 into the cornea.
(6)
A swimmer cannot see properly when she opens her eyes underwater. When underwater:
(i) why does the cornea not act as a lens? (ii) what is the maximum power of the eye? (iii) why do objects appear blurred?
(iv) explain how wearing goggles allows objects to be seen clearly.
