Concave vs. Convex — What's the Difference?
By Tayyaba Rehman — Updated on October 5, 2023
Concave is a surface curving inward. Convex is a surface bulging outward.
Difference Between Concave and Convex
Table of Contents
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Key Differences
A Concave shape or surface is characterized by its inward curvature, forming a shape similar to the interior of a cave. Conversely, a Convex shape or surface projects outward, similar to the exterior curve of a sphere, creating a bulge.
When considering mirrors or lenses, Concave and Convex each generate unique optical effects due to their distinct curvatures. A Concave mirror, for instance, converges light, while a Convex mirror disperses it, impacting how images are perceived and projected.
In geometry and daily observations, recognizing Concave and Convex surfaces aids in understanding the properties and functionalities of various objects. A Concave lens is thin in the middle and thick at the edges, while a Convex lens is thicker in the middle than at the edges, affecting their focusing properties.
Concave and Convex shapes also find utility in different practical applications due to their opposing curvatures. For instance, Concave surfaces are utilized in satellite dish designs to gather signals, while Convex surfaces are used in car side mirrors to provide a wider field of view.
Identifying Concave and Convex forms in architecture and design provides insights into structural and aesthetic intentions. A Concave facade may be employed to create a sheltering effect, while a Convex facade may be utilized to present an expansive and outward-reaching aesthetic.
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Comparison Chart
Curvature Direction
Inward
Outward
Example Shape
Cave
Bulge
Mirror Effect
Converges light
Disperses light
Lens Shape
Thinner in the middle
Thicker in the middle
Practical Application
Gathering signals (e.g., satellite dishes)
Expanding view (e.g., side mirrors)
Compare with Definitions
Concave
Inward-curving surface
The bowl has a concave bottom.
Convex
Domed or arched outward
The window displays a classic convex curvature.
Concave
Curved like a cave inside
A concave mirror converges light.
Convex
Rising or swelling outward
The convex bubble grew larger.
Concave
Indentation in a shape
The shield features a concave design for protection.
Convex
Projecting outward
Convex mirrors expand the field of view.
Concave
Hollowed or arched in form
The landscape has a concave depression.
Convex
Elevated and curved shape
The skateboard ramp is distinctly convex.
Concave
Curved like the inner surface of a sphere.
Convex
Bulging or curved outward surface
The lens has a convex shape.
Concave
A concave surface, structure, or line.
Convex
Having a surface or boundary that curves or bulges outward, as the exterior of a sphere.
Concave
To make concave.
Convex
Curved or bowed outward like the outside of a bowl, circle, or sphere.
Concave
Curved like the inner surface of a sphere or bowl.
Convex
Having an epigraph that is a convex set.
Concave
Not convex; having at least one internal angle greater than 180 degrees.
Convex
Having no internal angles greater than 180 degrees.
Concave
Satisfying the property that all segments connecting two points on the function's graph lie below the function.
Convex
Arranged such that for any two points in the set, a straight line between the two points is contained within the set.
Concave
Hollow; empty.
Convex
Any convex body or surface.
Concave
A concave surface or curve.
Convex
(gambling) A playing card made convex for use in cheating.
Concave
The vault of the sky.
Convex
(gambling) A small convex mirror used to cheat by observing other players' cards.
Concave
One of the celestial spheres of the Ptolemaic or geocentric model of the world.
Aristotle makes [Fire] to move to the concave of the Moon. - Thomas Salusbury (1661).
Convex
Rising or swelling into a spherical or rounded form; regularly protuberant or bulging; - said of a spherical surface or curved line when viewed from without, in opposition to concave.
Drops of water naturally form themselves into figures with a convex surface.
Concave
(manufacturing) An element of a curved grid used to separate desirable material from tailings or chaff in mining and harvesting.
Convex
A convex body or surface.
Half heaven's convex glitters with the flame.
Concave
(surfing) An indentation running along the base of a surfboard, intended to increase lift.
Convex
Curving or bulging outward
Concave
(skateboarding) An indented area on the top of a skateboard, providing a position for foot placement and increasing board strength.
Concave
(gambling) A playing card made concave for use in cheating.
Concave
To render concave, or increase the degree of concavity.
Concave
Hollow and curved or rounded; vaulted; - said of the interior of a curved surface or line, as of the curve of the of the inner surface of an eggshell, in opposition to convex; as, a concave mirror; the concave arch of the sky.
Concave
Hollow; void of contents.
As concave . . . as a worm-eaten nut.
Concave
A hollow; an arched vault; a cavity; a recess.
Up to the fiery concave towering hight.
Concave
A curved sheath or breasting for a revolving cylinder or roll.
Concave
To make hollow or concave.
Concave
Curving inward
Concave
Sloping inward
The concave facade offers a sheltered entrance.
Common Curiosities
What does Concave mean?
Concave describes a surface or shape curving inward.
Is a Concave lens thinner in the center?
Yes, a Concave lens is generally thinner in the center than at the edges.
Are satellite dishes Concave?
Yes, satellite dishes are Concave to focus signals to a single point.
Can a surface be both Concave and Convex?
A surface can have both Concave and Convex areas, but one area cannot be both.
Are Convex shapes used in car mirrors?
Yes, Convex mirrors are commonly used in car side mirrors to widen the view.
Is a Convex surface bulging outward?
Yes, Convex refers to a surface that curves or bulges outward.
Are Concave mirrors used in telescopes?
Yes, Concave mirrors are used in telescopes to focus light.
Do Convex mirrors diverge light?
Yes, Convex mirrors cause light rays to diverge, or spread out.
Can Concave surfaces create a sense of enclosure?
Yes, Concave surfaces can create a sheltering or enclosing effect in designs.
Are Convex lenses used in eyeglasses?
Yes, Convex lenses are used in eyeglasses to correct farsightedness.
Do Convex curves appear on architecture?
Yes, Convex curves are used in architecture for various aesthetic and functional purposes.
Can Concave shapes focus signals?
Yes, Concave shapes, like satellite dishes, focus signals to a point.
Do Convex mirrors create larger but distant images?
Yes, Convex mirrors create images that appear smaller and farther away.
Can Convex and Concave be used in lens combinations?
Yes, lenses with Convex and Concave surfaces are often used together in optical systems.
Is a bowl typically Concave?
Yes, bowls are typically Concave, curving inward to hold contents.
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Written by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
