Difference Between Concave and Convex Lens (With Table)

Concave vs Convex Lens

The key difference between Concave and Convex Lens lies in the fact that the concave lens refers to the lens which disperses the light rays when contacted with the 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.

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.

A concave lens is used for myopia to correct shortsightedness, but a convex lens is used to correct hyperopia to correct farsightedness.


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 1
Working of a 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.

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Convex Lens 1
Working of 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. 

 

Frequently Asked Questions (FAQ) About Concave and Convex Lens

Do cameras use convex or concave lenses?

A camera usually has a convex lens, but for higher quality purposes, both convex and concave lenses are used.

But it will be wrong to say that the camera uses a concave lens, as the primary lens is convex.

For a higher quality purpose concave lens is used with a convex lens. Basically, it depends on the type of camera as which lens has been used.

Which lens is present in the human eye?

The lens, which is present in the human eye, is convex. It helps the retina to focus on the refracted light to get a clear vision.

What type of image is formed by a convex lens?

A convex lens can form real, infinity, or virtual images. For example: When an object appears greater from the lens than the focal length, the image will be real.

When the object is equal to the focal length, the image will be infinity.

When an object appears lesser than the focal length from the lens, the image will be erect or virtual.

What type of image is formed by a concave lens?

The concave lens forms virtual images that are reduced in size. If you place an object at a distance that appears greater than the focal length, the image appears small or reduced in size.

How is a convex lens made?

A convex lens is made of transparent plastic or with glass. A convex lens has one surface which is curved outside.

A convex lens is usually used for binoculars or telescopes, which make the objects clear, even being distant.

A convex lens is also very useful for the treatment of hypermetropia or long-sightedness.

How is a concave lens made?

A concave lens is made of glass or also with transparent plastic.

The surface of a concave lens is curved inside. It makes smaller images to the viewer by causing the light to spread out.

They are used in flashlights and lasers in CD and DVD players.

A concave lens is also used in the treatment of myopia or short-sightedness.


 

Infographic

Concave Lens vs Convex Lens

 

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Conclusion

Concave and Convex lenses are used to produce clear and sharper images. They are used in various experiments, and most of the eyeglasses lenses are a combination of these two lenses. The telescopes, cameras, and lenses have made a revolutionary change in the world.

People can now perceive things differently, and this world has become colorful and beautiful. Both concave, as well as convex lenses, make different types of images and have a wide range of applications in the real world.

There are significant differences between the two, and these differences are important. Therefore, if one wishes to work with lenses, knowing the similarities and dissimilarities is crucial as it can hamper the way one works with lenses.


 

Word Cloud for Difference Between Concave and Convex Lens

The following is a collection of the most used terms in this article on Concave and Convex Lens. This should help in recalling related terms as used in this article at a later stage for you.

Concave and Convex Lens
Word Cloud for Concave and Convex Lens

 

References

  1. https://en.wikipedia.org/wiki/Lens#Types_of_simple_lenses
  2. https://www.universetoday.com/82338/concave-lens/
  3. https://www.universetoday.com/82589/convex-lens/

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