Definition – Convex Lens

A convex lens is designed so that a ray of light passes through the lens, and the focus is brought to a particular point. It Is also known as an optical device used to convert the transmitted light to form an image. It is made upon a spherical surface like a contact lens or the glass of a telescope that has an outside indentation. This is called the biconvex lens or the convex lens.

Features of Convex Lens

A convex lens is a converging lens that converges light rays that travel parallel to its principal axis.

Convex lenses are thicker in the middle area and are relatively thin at the sides. The edges of the lens are curved outward. Convex lenses are usually used in microscopes, magnifying glasses, eyeglasses, cameras to focus light for a clear picture, projectors, telescopes, multi-junction solar cells, peepholes on doors, binoculars, etc.

There are different convex lenses, and each lens is preferred for different purposes. Some of these types are plano-convex lenses, concave-convex lenses and double convex lenses. The objects can be placed at different positions for a convex lens. 

Uses of Convex Lenses

Convex lenses are used for a lot of things which includes both day-to-day and professional usage. A few common factors for which a convex lens could be used are as follows:

• Microscope and Magnifying Glass: Convex lenses are used in microscopes and magnifying glasses so that all the converging light focuses on a specific point.

• Camera lens: Convex lenses are used in cameras to focus more light on a clearer picture, and it helps to produce great photographic content.

• Telescopes: Similar to the microscope and magnifying glass, telescopes require the convex lens to bring in all the focus of light on the farther object.

• Eyeglasses: Convex lenses are used in eyeglasses so that it helps to bring the focus of light to the retina.

• Projectors: Projectors require magnification of images or videos to a larger screen. The generated images are inverted or magnified to provide better sights.

• Peep-Holes: Convex lenses are used in peepholes. The holes are tiny, and the convex lens magnifies the image present on the other side of the door.

• Binoculars: The purpose of binoculars is to see distant objects closer. So, the convex lenses help view a magnified version of the images.

The formula for Convex lens

The formula for convex lens is 1/f = 1/v – 1/u, here f is focal length, u is distance of object from the lens and v is distance of image from lens. The images formed may be real or virtual, and the total distance is taken as positive and the virtual distance as negative. These could be well understood with the help of a diagram. Here, the distances of each aspect are measured from the centre of the lens. For a convex lens, f is always of the positive quantity. 

For a convex lens, magnification M is positive for a virtual image and negative for a real image under magnification.

A few other formulas form part of other concepts related to the convex lens. Convex lens study material can be referred to for a clear view of the concepts.

Difference between Convex and Concave Lens

There are a lot of differences between a convex and a concave lens. Some major differences are as follows:

• A convex lens is thicker in the middle and has relatively thin edges, whereas a concave lens is thinner in the middle and thicker in the edges. 

• The curve of the convex lens is outward, whereas the curve of the concave lens is inward.

• Light rays diverge from a concave lens, whereas light rays converge from a convex mirror. 

• Comparing the length of focal of any convex lens is positive, whereas that of concave lense is negative.

• The image produced by a convex lens is either virtual or real and inverted, appearing closer. The image produced by a concave lens is virtual and erect, and the images that appeared are smaller and farther. The virtual images of convex lens are formed when the object is placed closer to the lens than to the focal point. 

• Convex lenses are used to treat hypermetropia, whereas concave lenses are used to treat myopia. 

Conclusion

Convex lenses and the nature of the images formed by them are suitable for professional purposes as well as day-to-day purposes. The usage of each type of lens for each purpose is well-determined. With the help of ray diagrams, one can understand the distinct features and their uses in detail in this topic. Concepts like measurement of focal length, calculating the magnitude of the image and determining the focal length are a few concepts that require in-depth learning. The usage of these lenses in various instruments has been distinguished properly to have an in-depth analysis.