A precision instrument maker can see a display 4 m away clearly, but markings on a component 20 cm away are blurred.
An eye test compares the changes that occur when the instrument maker and a person with normal vision look from the display to the component.
| Person | Ciliary muscles | Suspensory ligaments | Lens thickness when viewing the display in mm | Lens thickness when viewing the component in mm |
|---|---|---|---|---|
| person with normal vision | contract | slacken | 3.6 | 4.4 |
| instrument maker | contract | slacken | 3.6 | 3.8 |
Explain, using the information in the table, why the markings are blurred and how a spectacle lens would correct this.
102 exam-style questions on Edexcel GCSE Biology 2.4 The eye, covering 2.4.1 Structure and function of the eye and 2.4.2 Eye defects and their correction. Each one has a worked solution and a mark scheme showing where the marks go.