AQA GCSE Physics

Revision Notes

6.3.3 Magnification


  • The magnification of a lens is equal to the ratios of the image height and the object height

Magnification Equation, downloadable IGCSE & GCSE Physics revision notes

  • This equation can be rearranged with the help of a formula triangle:

Magnification Triangle, downloadable IGCSE & GCSE Physics revision notes

Magnification, image height and object height formula triangle

  • The magnification depends on:
    • The distance of an object from the lens
    • The power of the lens
  • The units for height are unimportant, provided that both the object and image are measured in the same units
    • For example, both in cm, or both in mm
  • Therefore, magnification does not have units as it is a ratio
  • If the magnification is:
    • > 1, then the image is magnified
    • = 1, then the object and image are the same size
    • < 1, then the image is diminished

Worked Example

A person sees an image from a magnifying glass.

Magnification Worked Example Questions, downloadable IGCSE & GCSE Physics revision notes

Calculate the magnification of this image. Clearly show your working on the diagram.

Magnification Worked Example Solution, downloadable IGCSE & GCSE Physics revision notes

Step 1: Measure the height of the object from the scale

The object is 10 cm

Step 2: Measure the height of image from the scale

The image is 20 cm

Step 3: Substitute values into the magnification equation

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Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.

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