Difference Between Concave and Convex Lens

A lens enables us to see things around us, to see different colors, and to make differences between various objects. Our eyes, through which we see the world, have a crystalline lens.

This lens is transparent in nature. This lens has a biconvex structure, and along with the cornea, it refracts light rays to be focused on the retina. 

Lens do both refract as well as a focus light.

The curve of a lens makes the whole difference as its shape determines in which direction and to what extent the light is going to bend. Based on its shape, a lens can be defined as a concave and convex lens.

The convex lens also is known as a converging lens as it converges the light to form an image on the other side.

Concave vs Convex Lens

The difference between Concave and Convex Lens is that the concave lens refers to the lens which disperses the light rays when contacted with the lens. A concave lens is used for myopia to correct shortsightedness, but a convex lens is used to correct hyperopia to correct farsightedness.

Concave vs Convex Lens

A convex lens refers to the lens through which light rays pass when contacted. In a concave lens, objects appear smaller and far whereas in convex lens objects appear bigger and large.

Comparison Table

Parameter of ComparisonConcave LensConvex Lens
DefinitionIt is a diverging lens that spreads out the light.It is a converging lens which converges the refracted rays.
CurveThe curve is outward in it.The curve is inward in it.
Image and ObjectsThe image formed is real, and the object appears closer and larger.The image formed is virtual, and the object appears smaller and at a great distance
Focal LengthThe focal length is positive.The focal length is negative.
Usage  Used to correct the problem of short-sightedness or myopia.  Used to correct the problem of farsightedness or hypermetropia.

What is Concave Lens?

Curiosity is the mother of invention. Every scientific experiment starts with a zeal to discover something new, and we can assume that the same interest brings the idea of the lens, their types, and, most importantly, their uses.

Objects could be perceived with different images and can be applied in many cases also. A concave lens has a thinner center and thicker edges. Its surface is inwardly curved. It spreads the light rays falling on its surface, and that is why it is also called a diverging lens.

There is a specific point where the light rays converge after getting reflected. This point is known as the principal focus of the concave lens.

At this point, the parallel light moving to the axis of the lens is focused.

The images formed by the concave lens are always virtual, upright, and smaller than the object. The size of the virtual images increases because the distance between the lens and object decreases.

Concave lenses are used in eyeglasses, telescopes, flashlights, side mirrors of cars and motorbikes, movie projectors, etc.

Concave Lens

What is Convex Lens?

The curiosity for the convex lens is more attractive as it can be used to start a fire with the help of the sun. Many children must have tried this exciting lens game after studying Physics.

A convex lens is those who are relatively thicker at the center but thin at the edges, and these edges are curved outward rather than inward.

A convex lens has the property of converting the beams of light rays, which are initially parallel to the principal axis to a point called the focus on the other side of the lens.

A convex lens can produce a virtual or real image according to the position of the object. If the purpose is located at a distance smaller than its focal length, then the image produced will be virtual and erect.

Whereas, if the object is lying at a distance equal to its focal length or greater than the focal length, than the image produced will be real and inverted. 

It is used to correct hypermetropia, i.e., long-sightedness in which a person is not able to see nearby objects. It is also used in making optical instruments like microscope, telescope and magnifying glasses, etc.

Being converging in nature, it is used in camera lens to focus light on a clear picture. Even the lens present in human eyes is also convex in shape that can change its focal length according to the position of the object and forms its image at the retina.

Convex Lens

Main Differences Between Concave and Convex Lens

  1. The simplest difference between a concave and convex lens is their physical appearance. Convex is thin at edges and thick at the center while a concave lens is thin at the center but thick at its edges.
  2. The curvature of a convex lens is outward-facing, whereas the curvature in a concave lens is inward-facing.
  3. The focal length of a convex lens is positive, while the concave lens has a negative focal length.
  4. A convex lens has converging nature as it merges the light passing through it and focuses them at a particular point. On the other hand, a concave lens has diverging nature as it diverges the light rays passing through it, i.e., it spreads the light rays. 
  5. A convex lens can form virtual as well as the real image of the object according to its distance from the lens, whereas the concave lens forms an only virtual image of the object.
  6. A convex lens is used to correct hypermetropia i.e., long-sightedness while concave lens corrects myopia i.e., short-sightedness. 
Difference Between Concave and Convex Lens


  1. https://www.universetoday.com/82338/concave-lens/
  2. https://www.universetoday.com/82589/convex-lens/
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