The main purpose of the convex lens is to converge the light coming from an external source, and as a result, the light is focused on the other side of the lens

1. Convex lens – uses, functions and types
Lenses work on the principle of refraction in order to converge or diverge
a ray of light, and in this way, they form an image. Refraction happens
when a ray of light passes from one medium to another, and during this,
it changes its speed and bends. A len s usually has one side that is curved.
Based on the curve of a lens, it is classified as either a convex or concave
lens.
Here we have talked about the working principle of a convex lens and how
it is used in different devices for varying purposes.
Convex Lens
This is the type of lens that has a curve in such a way that it is thin on the
edges, but when it comes to the center, the lens is rather thick. In other
words, if the surface of a lens is seen to be curved outside, then it is

2. identified as a biconvex lens. The main purpose of the convex lens is to
converge the ray of light coming in from an external source, and as a
result, the ray of light is focused on the other side of the lens, which
helps to form an image.
The point where the light converges is stated as the focus, and the focal
point is known as the distance that is covered from the center of the lens
to the focus. Since a convex lens is known to be the ray of light towards
one particular focal point, this lens is also known as a convergin g lens.
Type of images
Basically, a convex lens forms up two types of images, either real or
virtual images. Real images are the type of images that can be seen on a
screen, and they can be captured there. Only convex lenses are able to
produce real images, so the lenses that are part of o ur tv screens or
cinema screens that show us the captured image are basically using
convex lenses.

3. On the other hand, convex lenses are also known for making virtual
images as well. These are the type of images that we usually see through
the lens. They have a shorter distance from the focal point. For example,
the images we see while wearing spectacles are virtual images. When
convex lenses are added to spectacles, we view the image formed on the
lens, and we look at the image from there.
Magnification of convex lens
The magnification of a convex lens is basically the correlation between
the height of an image and the object. It enlarges the image of the given
object. The extent of magnification of the lens is referred to as the
magnification power of the lens. In this way, the magnification power
determines what will be the height ratio between the image and object
and how enlarged the image will appear to us. Let’s suppose
the magnification of the lens is set to 3. It will simply mean that the image
height of the object is 3 times more than the height of the object, as the
object has been magnified in the image with the help of the lens.

4. Image formation
The image that is formed by a convex lens is usually formed in such a way
that as we bring the object closer to the lens, the image formed gets
magnified in size. When the object is closest to the lens, at the point, the
formation is quite enlarged. There are some rules associated with image
formation by a convex lens. Here we have listed some basic rules that are
connected with the formation of an image by the use of the convex lens.
RULE 1: When refraction occurs, a light beam must go through the focus
of the lens. The light beam should be aligned or parallel to the principal
axis.
RULE 2: as a result of refraction, the light beam wil l not bend out when it
goes through the convex lens’s optical center. It will remain straight. Even
if the ray of light is going through the pathway of the principal axis of a
convex lens, it will remain straight as well without any bend.

5. RULE 3: as a result of refraction, the beam of light that has gone through
the focus of a convex lens will be becoming parallel to that of the
principal axis of the given convex lens.
Functions
Here we have discussed some of the functions associated with the convex
lens that is important for its normal working principles:
1. If the object is to be placed at an infinity position, then it has been
observed that the image that is formed by a convex lens is usually
inverted and real.
2. If the object is to be placed far off from the imaginary point, then
the image that is formed is found to be at a location between the
imaginary and focal point.
3. If the object is to be placed at a given imaginary point, then the
image that is formed is at the imaginary point is inverted and real.
In the case of size, the size of the image is the same as the object.
4. If we are to place the object in between the focal point and the
imaginary point, then the image formed in turn is far from the
imaginary point, and the image, in turn, forms up is real and
inverted, and in size, it is magnified.
Uses of convex lens
Based on their structure and working, convex lenses have a broad range
of uses. Some of these uses have been discussed below:
In magnifying glass
A magnifying glass helps us view the image formed in an enlarged form. It
is not actually enlarged, but the lens in the magnifying glass makes us

6. believe that the object that is behind the glass is actually big and
enlarged. The magnified image is created when light rays are passed from
the convex lens that is present in the glass. The extent of object
enlargement depends on the distance of the object from the focal point.
In the eyeglass
When the light is not focused properly from the eye lens onto the retina,
there can be a problem in image formation. This results in two kinds of
problems, i.e., nearsightedness and farsightedness. When we face the
problem of farsightedness, it is usually treated with the help of convex
lenses.
In the condition of farsightedness, the image is formed quite far away
from the retina, which makes the vision blurry. To fix that , a convex lens
is added to the eyeglass. When wearing eyeglasses with a convex lens, the
distance between the focal point and the lens is reduced, which makes it

7. easy for the lens to focus the light onto the retina, and hence a clear
image is then formed.
In the camera
In the camera, a convex lens is added to capture a perfectly focused
image. After adding the convex lens, the camera is able to magnify the
object properly to form a clear image. A camera does not contain a sin gle
lens only. There are a series of lens that are added to it that makes it
easy for the camera to focus and magnify clearly. Usually, a sandwich of
the lens is made—a concave lens between two convex lenses.

8. In a microscope
The purpose of a microscope is to magnify the object placed on it. Since
convex lenses are good at magnifying the object to form a better image, a
convex lens is added to the microscope. When the convex lens is added to
the microscope, it becomes easy to magnify even very small objects quite
easily.

9. Types of Convex Lenses
Convex lenses have several shapes and sizes based on their appearance
and working principle. They have been divided into several types. These
are the few types of convex lenses as discussed below:
Plano-convex lenses
The purpose of this type of convex lens is to focus the parallel light rays
into a single focal point. The reason these lenses are known as Plano -
convex is that Plano refers to the flat side of the lens, whereas convex
refers to the other outward curved side of the lens. In this way, the lens
has one flat and another curved side.
Since plano-convex lenses are used to magnify the object image when
they are added between the eye and the object, they are used in
microscopes and telescopes for magnification purposes. It is also added
to the eyeglasses in order to treat the problem of farsightedness. This

10. type of convex lens is also used in the process of material cutting via
laser. Since these lenses help to widen the laser’s cut width, it helps the
laser to make a more effective cut in the material.
Double convex lens
This type of lens is also known as a convex -convex lens. As the name
suggests, these lenses have a double -sided curvature in a way that they
are bulged outwards with a convex curve on both sides of the len s, unlike
the plano-convex lens that has a curve on the single side of the lens only.
A double convex lens can form a real and a virtual image as well. Although
the curve appearance might differ, the working principle of the double
convex lens is quite similar to that of the plano-convex lens as it also
focuses the light beams that are in a parallel manner to a single focal
point. The application of the lens can be like a plano -convex lens because
both offer the purpose of magnification.

11. Concave-convex lens
This is the type of lens that has the properties of both concave and
convex lenses. It is bulged outwards on one side while it is bulged
inwards on the other side of the lens. In this way, this type of lens is
identified as convex and concave both at the same time.
Common differences between Convex and Concave
Lens
The concave and convex lenses usually differ with respect to the physical
and general working properties. Based on their differences, they offer
different uses. Here is some common difference that is noted in the types
of lenses.

12. Converge and diverge
The main difference between the two types of lenses is that the concave
lens is known to diverge the ray of light that befalls its surface, and on
the other hand, the convex lens is known to converge the light rays that
fall on its surface.
Shape of the lens
The shape of both lenses differs, which brings changes to their physical
properties and appearance. Due to their difference in shape, their uses
differ. The shape of the concave lens is such that it bulges out from the
outward side and is thin inward.
Focal length

13. The focal length of both lenses differs in the way that a convex lens has a
positive focal length while, on the other hand, a concave lens has a
negative focal length.
Images formed
Both lenses form different types of images. The convex lens is usually
able to generate both types of images, i.e., real and virtual. It can form a
virtual image when we place the object in the center of the focus. On the
other hand, a concave lens is only able to generate an image that is
virtual. This formed-up virtual image is erect and usually smaller in
contrast to the object.
Object appearance
Owing to the shape of the lenses, the object appears different from both
lenses. Since the convex lens has a thick and bulged center, we can view
the object as being big and close to us, whereas the concave lens has a
plain thin center that makes the objec t appear tiny and at a distance.
Cure and treatment
Both of these lenses are used to correct the eyesight issues. Some people
have the issue of farsightedness, also known as hyperopia, while some
people have the issue of shortsightedness, also known as myo pia. The
convex lens is used for the treatment of hyperopia in people, and the
concave lens is used to treat myopia in people.
Conclusion
Lenses are used to either converge or diverge the ray of light that helps
to form an image when a certain object is pl aced in between. There are
two main types of lenses, concave lens, and convex lens. Convex lenses
are bulged out in the middle while it has thin edges, and it is used to form

14. both types of images, either real or virtual. When people have an eyesight
issue, then convex lenses are used to treat the issue of farsightedness.
Learn more about the functionality of lenses and how they serve different
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