Difference between the concave and convex Lens

Lens

The lens is the equipment used to diverge and converge light beams to visualize different objects. It is based on the principles of refraction, which causes convergence or divergence in the path of the ray of light. Thus, the rays are either scattered or concentrated to a central location on a surface. The size of an object can be enhanced or diminished based on the type of lens used. 

The lens is composed of transparent material like glass, and in the case of a simple lens, there is only one lens surface, while several lenses are combined around a central axis to form the composite lens.

Depending on the shape of the lens, they can be divided into two broad categories-
 

Convex lens-

The lens made of glass or plastic, designed so that the surface of the lens bulges out centrally, is known as the convex lens. The lens is called the positive lens, and it converges the light that passes through it. The central point at which the light rays converge is called the focal point.

Concave lens-

This is the kind of lens that is prepared from a transparent surface like glass or plastic and is designed such that the central surface is curved inwards. The lens is also called the diverging lens because when a ray of light or a beam hits the center of the lens, it is scattered in different directions. When a parallel beam of light is incident on a concave lens, most of the light undergoes divergence. The point from which the light rays diverge is called the focal point of a concave lens. The concentric lens is sometimes referred to as the diverging lens or concave lens in physics.

What are the Different Types of Concave and Convex lenses-

The concave lens can further be classified into three types that are

• Bi-concave
• Concavo-Plano
• Concavo-convex

The convex lens can also be classified into the following types-

• Biconvex lens
• Plano-convex
• Concavo-convex

Difference Between Concave and Convex Lens

Application of Concave and Convex Lenses:

Convex lens - ● Magnifying the image-

A convex lens is used to magnify and enlarge the size of the image formed. If you place the object on one side of the lens closer to the focal point, you shall notice that the image is formed on the same side of the object but is magnified to a great extent. The image formed is virtual, erect, and enlarged. Such a lens finds its application in the magnifying glasses prepared to view the enlarged images of microscopic objects.

Used to treat Hypermetropia-

When the eyes' natural lens fails to focus the light of the objects on the retina properly, the doctors recommend eyeglasses. The problem of near or farsightedness can be rectified using proper lenses. The convex lens is used to heal the problem of farsightedness, also known as Hypermetropia. Here, the light rays are shortened by bending the rays, and thus the focal point is allowed to fall on the retina of the eyes. This reduces the focal length and, in turn, helps the person to obtain a clear vision of distant objects.

Concave lens- ● Used in Curing the Problem of Nearsightedness

When a person suffers from nearsightedness or myopia, they are suggested to get eyeglasses with concave lenses, which diverge the beam of light and can cure the issue. Using a pair of glasses makes it possible to obtain the focal point on the retina and view the near objects.

Used in Flashlights and Torches-

The lens used in the flashlights is a concave lens that is placed in the path of the light beam, and it diverges the rays so that in darkness, the beam of light is scattered over a large surface, and one can see things clearly even in darkness. The beam's diameter is enhanced, and it covers a larger surface allowing better visualization of objects.

NCERT Solutions For Class 10 Science Chapter 10, light reflection and refraction talks in detail about different types of mirrors including concave, convex mirrors, concave and convex lens along with the difference between them.