Magnification (Oxford AQA IGCSE Physics)
Revision Note
Written by: Ann Howell
Reviewed by: Caroline Carroll
Magnification
The magnification produced by a lens may be calculated using the equation:
This equation can be rearranged with the help of a formula triangle:
Formula triangle for magnification
The magnification of a lens depends on:
The distance of an object from the lens
The power of the lens
Magnification is a ratio and has no units
Both the object and image must be measured in the same units
For example, both in cm, or both in mm
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 through a magnifying glass.
Calculate the magnification of this image. Clearly show your workings on the diagram.
Answer:
Step 1: Measure the height of the object from the scale
The object is 10 cm
Step 2: Measure the height of the image from the scale
The image is 20 cm
Step 3: Substitute values into the magnification equation
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