Magnification (OCR GCSE Physics A (Gateway Science Suite)): Revision Notes
6.3.3 Magnification
Magnification
When an object is magnified, a virtual image of the object is created that is larger than the object itself. The image is called a magnified virtual image.
For magnification to occur, the object must be closer to the lens than the principal focus.
You can calculate how much the image has been magnified (increased size) using the following formula:
Magnification is a ratio and so it has no units. If a virtual image has a negative magnification, this means the image is smaller than the object.
Example: Calculating Image Size Using Magnification A flower is measured to be 3 cm tall. A magnifying glass with a magnification of 44 is used to view the flower. How tall does the flower appear to be? [2 marks]
Magnification equation:
Rearrange to find the image size:
Image size magnification × object size = 4×3 cm
= 12 cm