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5.1 Reflection, refraction and lenses

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Question 11

The equation relating the power of a lens to its focal length is:

power (in dioptres)=1focal length (in metres) \text{power (in dioptres)} = \frac{1}{\text{focal length (in metres)}} power (in dioptres)=focal length (in metres)1​

An optometrist prescribes a corrective lens with a power of 2.5 dioptres.

Calculate the focal length of this lens in cm.

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Markscheme

5.1 Reflection, refraction and lenses Questions

  1. GCSE
  2. /Physics
  3. /5.1 Reflection, refraction and lenses

24 exam-style questions on Edexcel GCSE Physics 5.1 Reflection, refraction and lenses, covering 5.1.1 Reflection, refraction and total internal reflection, 5.1.2 Specular and diffuse reflection, 5.1.3 Colour of light: absorption and filters, 5.1.4 Lenses: power, focal length and shape, 5.1.5 Ray diagrams for converging and diverging lenses, and 5.1.6 Real and virtual images. Each one has a worked solution and a mark scheme showing where the marks go.

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