For each of the patients at an optician, a diagram is made to show where light rays focus. Fig. 1 shows the eye of patient R viewing a distant road sign wit...
Question 1 Report
For each of the patients at an optician, a diagram is made to show where light rays focus. Fig. 1 shows the eye of patient R viewing a distant road sign without spectacles. The rays entering the eye are parallel. The optician must decide whether a concave or convex lens should be placed in a spectacle frame to allow the person to see clearly.
(a) Describe where the light rays meet in relation to the retina. [2]
(b) Name the vision defect shown by patient R. [1]
(c) Which type of spectacle lens should the optician prescribe? [1]
(d) Explain how this lens changes the path of light so that a clear image forms on the retina. [3]
(e) State one structure in the human eye that changes shape during focusing. [1]
(f) Complete this sentence. The image formed on the retina is upside down and __________. [2]
Answer Details
(a) The parallel rays meet behind the retina, rather than on the retina. [2]
(b) This is long-sightedness, also called hyperopia. For distant vision, the eye does not converge the rays sufficiently before they reach the retina. [1]
(c) The required spectacle lens is a convex lens. [1]
(d) A convex lens converges the light rays before they enter the eye. Therefore the rays are bent more strongly overall by the spectacle lens and eye lens together, moving the focus forwards onto the retina. A sharp image can then form. [3]
(e) The lens changes shape during focusing. [1]
(f) The retinal image is upside down and real and diminished (smaller). [2]
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