# 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

### Geometry

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

## Concave and Convex Definitions

#### Concave

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

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

#### Concave

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

#### Convex

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

#### Concave

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

#### Convex

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

#### Concave

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

#### Convex

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

#### Concave

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

#### Convex

Convex lenses are used to converge light rays for magnification.

#### Concave

Curved like the inner surface of a sphere.

#### Convex

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

#### Concave

A concave surface, structure, or line.

#### Convex

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

## FAQs

#### 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.