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Concave vs. Convex: What's the Difference?

Edited by Aimie Carlson || By Janet White || Published on January 7, 2024
Concave refers to a surface curving inward, like the inside of a bowl, while convex means a surface curving outward, like the exterior of a sphere.

Key Differences

Concave surfaces curve inward, resembling a cave, and are used in optical devices like telescopes to focus light. Convex surfaces, curving outward, are found in lenses like magnifying glasses to disperse light.
A concave shape has an inward curve, making it appear as if a segment is removed, like a crescent moon. In contrast, convex shapes bulge outward, resembling a dome or the surface of a balloon.
Concave mirrors concentrate light and produce magnified images, used in makeup mirrors for detailed view. Convex mirrors, curving outward, provide a wider field of view and are used in vehicles for rear-view perspective.
In mathematics, a concave curve dips inward, like a valley in a graph, representing a specific set of data points. A convex curve, on the other hand, swells outward like a hill, representing a different data distribution.
In physics, concave surfaces reflect light inward, focusing beams to a point, essential in devices like satellite dishes. Convex surfaces scatter light, spreading beams outward, used in streetlight reflectors for broad illumination.

Comparison Chart


Inward curving
Outward curving

Mirror Type

Reflects and magnifies (e.g., shaving mirrors)
Disperses and shrinks (e.g., security mirrors)

Lens Effect

Converges light rays (e.g., telescope lenses)
Diverges light rays (e.g., peephole lenses)

Surface Appearance

Appears like a cave or a hollow
Appears like a bulge or a protrusion


Curves inward, resembling a cave or bowl
Bulges outward, resembling a dome or hill

Concave and Convex Definitions


Concave refers to a surface or shape curving inward.
The concave design of the dish antenna helps to focus signals at a central point.


Convex refers to a surface or shape curving outward.
The convex lens in her microscope magnified the cells.


Concave mirrors converge light to a focal point.
The dentist used a concave mirror to inspect the patient's teeth more closely.


Convex structures have an outward curvature.
The convex hull of the boat helped it glide smoothly over the waves.


Concave shapes resemble a hollow or a void.
The concave valley between the hills formed a natural amphitheater.


Convex shapes resemble a bulge or protrusion.
The convex surface of the bubble reflected the sunlight beautifully.


A concave lens disperses light rays, causing them to diverge.
The concave lens in his glasses made his eyes appear smaller.


A convex mirror spreads light, allowing for a wider view.
The store installed a convex mirror for better aisle surveillance.


Concave structures have an inward curvature.
The concave ceiling of the cave created an echo.


Convex lenses are used to converge light rays for magnification.
His reading glasses had convex lenses to aid his vision.


Curved like the inner surface of a sphere.


Having a surface or boundary that curves or bulges outward, as the exterior of a sphere.


A concave surface, structure, or line.


Curved or bowed outward like the outside of a bowl, circle, or sphere.


Do convex lenses make images appear larger or smaller?

Convex lenses generally make images appear larger.

Are concave shapes common in nature?

Yes, concave shapes like valleys or cave entrances are common in nature.

Can convex shapes be found in architecture?

Yes, convex shapes like domes are common in architecture.

Is a concave mirror good for detailed viewing?

Yes, concave mirrors magnify and are good for detailed viewing.

What are convex lenses used for?

Convex lenses are used to converge light rays for magnification.

Are convex surfaces used in vehicle mirrors?

Yes, convex mirrors are used in vehicles for a wider rear view.

Can both concave and convex be used in mirrors?

Yes, concave mirrors focus light, while convex mirrors spread it for a wider view.

Are concave mirrors used in telescopes?

Yes, concave mirrors are often used in telescopes to focus light.

What is a concave surface?

A concave surface curves inward, like the inside of a bowl.

Is the exterior of a sphere considered convex?

Yes, the exterior of a sphere is a typical example of a convex shape.

Is a convex surface ideal for a security mirror?

Yes, the wide view of a convex mirror is ideal for security purposes.

Can concave lenses be used in eyeglasses?

Yes, concave lenses are used in eyeglasses for specific vision corrections.

How do concave lenses affect light rays?

Concave lenses cause light rays to diverge or spread out.

What's the visual effect of a convex mirror?

Convex mirrors create a smaller, wider field of view.

Do concave surfaces have a magnifying effect?

Yes, concave surfaces like mirrors can magnify images.

Are convex shapes more common in man-made objects?

Convex shapes are prevalent in both man-made and natural objects.

Can concave structures concentrate sound?

Yes, concave structures can focus and amplify sound.

Are convex mirrors used in public spaces?

Yes, convex mirrors are used in public spaces for safety and surveillance.

Do concave mirrors have a wide field of view?

No, concave mirrors focus light, limiting their field of view compared to convex mirrors.

Do concave lenses have a spreading effect on light?

Yes, concave lenses spread light rays, causing them to diverge.
About Author
Written by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

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