A camera technician compares the focusing system of a camera with the eye. Fig. 1 shows an eye looking at a nearby mobile phone. The phone is 25 cm from the...
Question 1 Report
A camera technician compares the focusing system of a camera with the eye. Fig. 1 shows an eye looking at a nearby mobile phone. The phone is 25 cm from the eye, so the image must be focused sharply on the retina rather than in front of it or behind it.
(a) Complete the table to compare the lens of the eye when viewing a nearby object and a distant object. [2]
| Object viewed | Shape of lens | State of suspensory ligaments |
|---|---|---|
| Nearby mobile phone | ________ | slack |
| Distant road sign | thin / less curved | ________ |
(b) Explain how ciliary muscles and suspensory ligaments make the lens thicker when the mobile phone is viewed. [3]
(c) State two structures, other than the lens, that light passes through before reaching the retina. [2]
Answer Details
(a) For a nearby mobile phone, the lens is thick or more curved. For a distant road sign, the suspensory ligaments are tight or stretched. [2]
(b) To view the nearby phone, the ciliary muscles contract. This makes the suspensory ligaments slack, allowing the lens to become thicker and more curved. The thicker lens refracts light more strongly so that the image is focused on the retina. [3]
(c) Two structures light may pass through before reaching the retina are the cornea and aqueous humour. [2] The pupil and vitreous humour are also acceptable.
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