Adjusting the focus - The shape of the lens is altered , to make it bend light rays by different amounts.
- The thicker the lens, the more it bends the light rays.
- The thinner it is , the less it bend them.
- This adjustment in the shape of the lens, to focus light coming from different distances, is called accommodation .
- Figure 12.18 shows how the shape of the lens is changed.
- It is held in position by a ring of suspensory ligaments.
- The tension on the suspensory ligaments, and thus the shape of the lens , is altered by means of the ciliary muscle.
- When this muscle contracts, the suspensory ligaments are loosened.
- When it relaxes, they are pulled tight.
Ziad ahmed – IGCSE-AS-A-Level-IB Biology Teacher WhatsApp: +974-55596985
Ziad ahmed – IGCSE-AS-A-Level-IB Biology Teacher WhatsApp: +974-55596985
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