# 6.3.3 Magnification

### Magnification

• 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

#### Worked Example

A person sees an image from a magnifying glass. Calculate the magnification of this image. Clearly show your working on the diagram. 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  ### Author: Katie

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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