A convex lens is a converging lens that converges rays of light that are traveling parallel to its principal axis. Convex lenses are thick across the middle and thin at the upper and lower edges. Optical instruments like microscopes, projectors, cameras magnifying glasses, eyeglasses, etc use convex lenses. In this article, we discuss the ten uses of convex lenses.
Uses of convex lenses
- Magnifying glasses
- Eye glasses
- Optical microscopes
- Projectors
- Cameras
- Human eye
- Telescopes
- Multi-junction Solar cells
- Peep holes in doors
- Binoculars
Magnifying glasses
A magnifying glass focuses all the incoming light on a particular point called the focal point. This focal point is located in front of the lens. The object is magnified when the distance between it and the lens is less than the focal length. When an object is at the focal point, we get the maximum magnification. You might have noticed that to get a good magnification you have to bring the glass near the object but not very very near, this is the focal point of the convex lens.
Eyeglasses
A person has difficulty in viewing objects when the natural lens in the eye is not able to focus the light on the retina. Hyperopia is a condition when a person cannot clearly view objects near the eye. But, the person can view far-off objects clearly. This condition is also called far-sightedness. This condition may arise due to the inability of the ciliary muscles to adjust the focal length of the eye lens. The light coming from the objects is focussed at a point beyond the retina. Hence, there is a need to converge the light rays and focus them on the retina. A convex lens in front of the eye will converge the light rays to focus on the retina for better viewing.
Optical Microscopes
Very small objects like microfibers, bacteria, microparticles, microtextured surfaces, etc can be viewed easily using an optical microscope. A convex lens has the ability to magnify objects. A combination of 3 lenses is used in order to increase the magnifying power of a simple microscope. Compound microscopes have an even higher number of lenses to increase the magnifying power of the microscope to view microorganisms.
Projectors
Projectors are optical devices that have the ability to project images or videos on large screens. The idea behind the working of a projector is the magnification of the image or video played on the film. The image generated by the lens is magnified and inverted. The film is always loaded in an inverted position in order to compensate for the inverted image produced.
Optical camera
Cameras use convex lenses to focus an image and magnification. By moving the convex lens we can adjust the magnification of the camera. By this action, we are adjusting the focal point to get better magnification. In a similar way video cameras, webcams, etc also use convex lenses.
Human eye
When are able to see an object because it emits light or is able to reflect light. The light from the object reaches our eye and is processed into an image. The light first enters our eye lens which is convex. The is a good example of the use of convex lenses by nature. The natural lens in our eyes focuses the incoming light onto the retina. The retina is a screen-like tissue that captures the light. The light is converted into neural signals by various cells present in the retina. These neural signals are processed by the brain. The inability of the lens to focus the light onto the retina results in farsightedness or nearsightedness issues.
Telescope
The telescope is used for viewing objects which are very far off like planets in the solar system. There are two types of telescope: refracting telescope and reflecting telescope. Refracting telescope work on convex lenses and reflecting telescope work on mirrors. The refracting telescope consists of two convex lenses. The first lens converges all the light and the second lens magnifies the image. You can read more at https://spaceplace.nasa.gov/telescopes/en/.
Multi-junction solar cells
Convex lenses are used as concentrators for concentrating more light radiations which finally increases the power output of the solar cell. You can read more on this in this article titled “The use of convex lens as a primary concentrator for multi-junction solar cells“.
Peep-holes
Peepholes are small holes placed on doors. They can be also in secret places for security purposes. The hole is very small, but the convex lens placed in the hole magnifies the image that is on the other side.
Binoculars
Binoculars can be used to view magnified images of far-off objects. They are used in the military, in stadiums, bird watching, etc. The working principle of a binocular is similar to a telescope.
What are the everyday uses of convex lenses?
Every one of us sees through our eyes. The human eye itself is an example of the use of convex lenses. The camera is another device that we use regularly nowadays. Barcode readers also use convex lenses. Other common uses of convex lenses include eyeglasses, scientific equipment, peepholes, etc.
Can convex lenses burn objects?
The intensity of the heat generated by the convex lens depends on the intensity of the radiation and the size of the lens. You can try this experiment by holding a magnifying glass above a piece of paper in broad sunlight light. After a few minutes, you can see small burnt spots on the paper.
What is the difference in the application of convex mirrors and convex lenses?
Convex lenses find use when there is a need to converge light rays to produce an image. When the object is a distance greater than the focal length then the image produced is real and can be captured on a screen. Concave lenses are mostly used in magnification applications like microscopes, telescopes, binoculars, etc.
Convex mirrors are spherical mirrors that give a virtual and erect image. But the image by a convex mirror cannot be captured on a screen. Side-view mirrors in vehicles, driveways, etc use a convex mirror.
What is the difference in application of convex lenses and concave lenses?
Convex lenses are used for magnifying applications or applications where light needs to be converted to a specific point. Devices like microscopes, telescopes, etc use convex lenses. Concave lenses are used for applications where light rays need to diverge. Devices like flashlights use a concave lens where the beam of light is diverged to get wide light coverage.
Are electronic magnetic lenses similar to convex lenses?
Electromagnetic lenses converge electron beams in an electron microscope and are different from optical lenses.
