Explain convex & concave mirrors

Updated July 19, 2017

Convex and concave mirrors differ from flat mirrors in that they distort reflections by the nature of their shape. Convex and concave mirrors are manufactured with the same components and use the same principles as flat mirrors, but they alter the size of reflected images.


Convex mirrors are often used as security mirrors to help protect easily stolen items; for instance, in retail establishments. Concave mirrors are most commonly used in light sources such as car side mirrors.


Convex mirrors bulge outwards or towards the object they are reflecting. Concave mirrors curve inward or away from the object they are reflecting.


Convex and concave mirrors both distort images; however, they have different effects. Convex mirrors magnify images and cause light to diverge. Concave mirrors shorten images and focus light into parallel beams.


Convex and concave mirrors have one feature in common: they are made from a substrate with a reflective coating. Modern mirrors use a silver nitrate reflective coating applied to back of the substrate that is as thin as paper and protected by a silicone-based paint. Glass is the most commonly used substrate due to its rigidity and transparency, according to

Fun Fact

Both convex and concave mirrors are used in fun houses and are often combined to create distorted reflections.

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About the Author

Keith Chew is a member of the Pennsylvania Army National Guard and served in support of Operation Enduring Freedom in Afghanistan. He was an associate editor for the "College Hill" and contributing columnist for the "Stroud Courier." Chew graduated from Excelsior College with a Bachelor of Arts.