Difference between concave or convex

In the exploration of concave and convex, we embark on a journey through the realms of geometry and physics, where these terms play pivotal roles in describing shapes and surfaces. Concave and convex are adjectives that describe the curvature of a surface or line, each possessing unique characteristics and applications across various fields.

Quick Facts Table

DefinitionCurving inwardCurving outward
Example UsesMirrors, lenses, satellite dishesMirrors, lenses, security cameras
ShapesBowl-like, cavesDome-like, hills
Light ReflectionDiverges light raysConverges light rays
In GeometryInterior angle greater than 180°Interior angle less than 180°

Difference Between Concave and Convex

Definition of Concave

Concave surfaces curve inward, resembling a cave or a bowl. They are characterized by their ability to diverge light rays that hit their surface, spreading them outwards.

Definition of Convex

Convex surfaces, on the other hand, curve outward, akin to the outer surface of a sphere or a bubble. They converge light rays, focusing them to a point.

Origin of Concave

The term concave originates from the Latin words “con” (meaning ‘together’) and “cavus” (meaning ‘hollow’). It describes surfaces that are hollowed inward.

Origin of Convex

Convex comes from the Latin “convexus,” meaning “curved or rounded.” It refers to surfaces that bulge outwards.


  • Concave: /ˈkɒn.keɪv/
  • Convex: /ˈkɒn.veks/

Comparing Concave and Convex

When comparing concave and convex surfaces, it’s essential to note the direction of their curvature. Concave surfaces have an inward curvature, making them capable of diverging light, whereas convex surfaces bulge outwards, focusing light. This fundamental difference affects their applications in optics, architecture, and design.

Comparison Table

Light BehaviorDiverges light raysConverges light rays
Visual EffectObjects appear largerObjects appear smaller
Uses in OpticsTelescopes, binocularsMagnifying glasses, cameras

Usage in Sentences with Explanations

Use of Concave in Sentences

  1. The concave mirror in the telescope magnifies distant stars.
    • Explains how concave mirrors are used in telescopes to enlarge distant objects.
  2. Her spoon’s concave surface reflected a distorted image of her face.
    • Demonstrates the characteristic of concave surfaces to distort reflections.
  3. The skateboard ramp’s concave design helped him perform tricks.
    • Highlights the application of concave shapes in enhancing the functionality of structures.
  4. The concave lens in his glasses corrected his vision.
    • Shows the use of concave lenses in eyeglasses to diverge light, correcting certain vision problems.
  5. The artist used a concave shape to create an illusion of depth.
    • Illustrates the use of concave curvatures in art to create visual effects.

Use of Convex in Sentences

  1. The convex mirror at the store’s corner provided a wide-angle view.
    • Describes the use of convex mirrors for security and surveillance to see a broader area.
  2. She used a convex lens to focus sunlight and start a fire.
    • Shows how convex lenses can converge light rays to a focal point, generating heat.
  3. The building’s convex facade was designed to reflect the sky.
    • Highlights architectural use of convex surfaces for aesthetic purposes.
  4. His convex shield deflected the arrows away.
    • Demonstrates the practical application of convex shapes in historical armor to divert forces.
  5. The convex bump on the road slowed down the speeding cars.
    • Explains the use of convex shapes in traffic calming measures to reduce vehicle speed.


Understanding the differences between concave and convex is crucial across various disciplines, from physics and geometry to design and architecture. While concave surfaces curve inward and are adept at diverging light, convex surfaces bulge outward, focusing light rays. Each has its unique applications and effects, demonstrating the versatility and importance of curvature in our daily lives and in the technological advancements we continue to make.

Commonly Asked Questions

  • What are some common uses of concave surfaces?
    • Mirrors in telescopes, lenses in certain eyeglasses, and satellite dishes.
  • How do convex surfaces affect light?
    • Convex surfaces converge light rays, focusing them onto a point.
  • Can both concave and convex shapes be found in everyday objects?
    • Yes, everyday items like spoons, bowls, and glasses often feature concave and convex shapes.
  • What role does curvature play in optical devices?
    • Curvature determines how the device manipulates light, affecting magnification, focus, and image distortion.
  • Why are convex mirrors used for security purposes?
    • Because they provide a wider field of view, allowing for better surveillance of large areas.

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