Difference Between Convex and Concave Lens

The lens is understood as a curved and transparent piece of glass or plastic, which focuses and refracts light rays in a certain manner. The curvature of the object ascertains the extent to which light is bent and in which direction. They are used in spectacles, microscope and telescopes. Based on the shape, the lens can be grouped as a convex lens or concave lens. The former brings together the parallel beam of light, while the latter disperses it.

So, the point of focus in case of the convex lens is the point where all the light rays meet, i.e. point of convergence, but if we talk about the concave lens, the focal point is the point from where the light rays seem to diverge, i.e. point of divergence.

Let’s understand the difference between convex and concave lens, with the help of the diagram below.

Content: Convex Lens Vs Concave Lens

1. Comparison Chart
2. Definition
3. Key Differences
4. Conclusion

Comparison Chart

Basis for Comparison	Convex Lens	Concave Lens
Meaning	Convex lens refers to the lens which merges the light rays at a particular point, that travels through it.	Concave lens can be identified as the lens which disperses the light rays around, that hits the lenses.
Figure
Curve	Outward	Inward
Light	Converges	Diverges
Centre and edges	Thicker at the center, as compared to its edges.	Thinner at the center as compared to its edges.
Focal length	Positive	Negative
Image	Real and inverted image.	Virtual, erect and diminished image.
Objects	Appear closer and larger.	Appear smaller and farther.
Used to	Correct hyperopia.	Correct myopia.

Definition of Convex Lens

Convex Lenses are the lenses that feel massive at the centre than at the edges. The curve of the lens is outward, and as the light beams pass through the lens, it refracts them and brings them together, resulting in the convergence of light, due to which it is also named as a converging lens. Look at the figure given below:

So, the point where the light rays meet is known as a focal point, or principal focus and space amidst the centre of the lens and the principal focus is the focal length. Further, it generates a real and inverted image, but it can also form a virtual image when the object is placed too close to the lens. Such lenses are used to focus a beam of light on making the object look clearer and larger.

Example: The lenses of a camera are a convex lens, as the light rays focus on person or object being captured.

Definition of Concave Lens

Concave lenses represent the type of lenses which are slender at the centre than at the borders. The shape of a concave lense is round inward that bends the beams outward, causing divergence of the rays of light falling on it, so it is known as a diverging lens. This also makes the object look smaller and farther than they really are and the image formed is virtual, diminished and upright.

As you can see in the given figure, the light rays appear to be diverging from a virtual point, which is known as principal focus or focal point. Further, the length between the focal point and the centre of the lens is called focal length.

Example: Concave lenses are used in the side mirrors of cars and motorbikes. They can also be used in movie projectors to spread the image.

Conclusion

So, with the above examples and figures, you might have got a clear understanding of the difference between the two types of lenses. Many times, convex and concave lenses are used along to produce sharper, clear and better images.