Magnification (AQA GCSE Physics)

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

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

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

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