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2 marksPhysics of the Ear and Eye

CAPE Physics Unit 1 · 2009 · Paper 2 · Question 5(c)(iii)

At age 45, a person uses reading glasses with a power of 2.0 D to read at 25 cm. By age 55, she needs to hold her newspaper at 40 cm to see clearly with the same glasses.

Calculate the power of the lens of the reading glasses now required so that she can again read at 25 cm.

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Other parts of this question

  1. 5(a)(i)Explain what is meant by 'Accommodation' as it relates to the human eye.[1 mark]
  2. 5(a)(ii)Explain what is meant by 'Depth of focus' as it relates to the human eye.[1 mark]
  3. 5(b)(i)Name the student's eye defect.[5 marks]
  4. 5(b)(ii)Copy Figure 3 onto your answer booklet. On the copied diagram, draw a ray diagram to illustrate the paths of two light rays from a point object at the normal…[5 marks]
  5. 5(b)(iii)Draw a second ray diagram to show how a lens may be used to correct the defect for an object set at 25 cm from the eye.[5 marks]
  6. 5(c)(i)Calculate the position of her near point at age 45.[4 marks]
  7. 5(c)(ii)Calculate the position of her near point at age 55.[2 marks]

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