[Physics Class Notes] on Uses of Concave Lens Pdf for Exam

A human is a natural optical lens that helps us see real-life objects with exact color distinctions. 

However, a few people lose the ability to see far/near objects, for them, a concave/convex lens (resp.) works as a helping source to fulfill their clear vision dreams.

A concave lens is a diverging lens that helps people view objects at large distances if they are dealing with Myopia; however, for people dealing with hypermetropia, a converging lens, convex lens is used, which we will discuss in this article.

We will also discuss the application of concave lenses with the uses of a concave and convex lens.

Concave Lens

A concave lens is one that is thicker at the edges and thinner in the centre. This type of lens bends light rays outwards. A concave lens is also known as a diverging lens as it diverges the light rays. It is made up of a number of prisms, with the base of each prism pointing away from the lens’s centre. The lens’s central section is a simple parallel-sided glass.

Light rays can pass through the parallel-sided glass slab without deviating.

The upper portion of the lens deviates light rays upwards, while the lower portion deviates light rays downwards. These lenses are used in those types of glasses that are known to correct the defects of vision i.e., myopia and hypermetropia. Materials used to make these lenses can either be glass or plastic, which are then polished and eventually moulded into different shapes. In contrast to a prism, which refracts light without focusing, a lens can focus light to form an image. 

Types of Concave Lens

The following are the different types of concave lenses:

1. Double concave

2. Plano concave

3. Convexo-concave

The Formula of Concave Lens

To know which type of image is created by a concave lens, the lens formula of that concave lens is used. It is also used to identify the position of the image. The formula for the concave lens is as follows:

1/f=1/v +1/u

Where,

‘f’ = the focal length 

‘v’ = distance of the image. 

‘u’ = distance of the object. 

Uses of Concave Lens

1. In a Telescope

Concave lenses are magnifiers found in telescopes and binoculars. The object is magnified by the concave lenses. Concave lenses are used before or in the eyepiece of telescopes and binoculars to help people focus more clearly.

2. Applied to Glasses

Concave lenses are used to correct myopia, also known as nearsightedness. Concave lenses in spectacles are used to compensate for the shortage by spreading light rays out before they reach the eyeball. This improves the person’s ability to see items in the distance.

3. In use in Peepholes

Peepholes are security devices that provide a 360-degree view of objects or areas outside of walls or doors. They are also known as door viewers. A concave lens is used to reduce the proportions of an object while providing a wider view of the object or area.

Concave and Convex Lens

We find the application of concave lens in treating vision issues and for that, we find the uses of a concave lens in daily life; let’s understand how:

A concave lens is used to treat myopia because the lens diverges the parallel light rays coming from distant objects. Therefore, a virtual image forms at a distant point of the myopic eye. 

Now, that the light rays are at the proper distance, the objects can be easily focused onto the lens, and a clear image is thus formed on the retina.

Below is the diagram to illustrate one of the concave lens examples on myopic eye-correctness (nearsightedness):

Convex Lens

A person who can view far objects clearly, but when it comes to viewing nearby objects, he/she fails to get a clear vision; let us understand what is the use of convex lenses here?

If a person is hypermetropic, the image of a nearby object forms behind the retina. This means that light is focused too far back in the eye that causes things that are close up to appear blurred.

At this moment, a convex lens works as a gold mine for people dealing with farsightedness. 

When a ray of light comes from the distant source is reaching the retina, before it reaches, the convex lens converges and works as a pathway for these rays to converge on the retina.

Below is the diagram to illustrate one of the convex lenses examples:

Now, let’s understand what are the uses of a concave lens followed by a convex lens, and also understand the 5 uses of concave and convex lenses.

Uses of Concave and Convex Lens

So, we will first start with the uses of concave lens Class 10:

We find many uses of a concave lens in daily life, the first two uses of the concave lens are:

A concave lens works as a safety factor for driving at night. This lens diverges the light to far distances that help in a clear view of the far vehicles at night.

We find a small lens fixed in the middle of our doors to view who ranged our doorbell, yes, these are the peepholes to peep who is outside the door. Here, the concave lens gives us a panoramic view of the person standing just opposite the door.

The Rest Three Uses of Concave Lens are:

Various devices like scanners, medical equipment, and CD and DVD players use laser beams. Since laser beams are highly-focused and we use small concave lenses to widen the laser beam to sharply access a specific area.

(About it, we have discussed in the above text on nearsightedness).

Uses of Convex Lenses

When the rays enter the convex lens of the magnifying glass, these rays focus on a specific focal point at the center of it.

(About this, we discussed in the above text on farsightedness).

Most of the cameras that we use have convex lenses, while a few have concave lenses.

Convex lenses help focus on the image well and magnify these at the same time.

Convex lenses are also called microscopic lenses. 

A simple microscope usually has three lenses, out of which, one (convex lens) produces an inverted and magnified image of microorganisms like bacteria, amoeba, etc.

Convex lenses are widely used for multi-junction electric cell. The lens is added above the Fresnel lens to increase the output power of the setup and retrieve the requirement for the employment of solar trackers. 

Interesting Fact

In cameras, we find the uses of a concave and convex lens to get clear images in photography.

To ameliorate the quality of photographs, camera manufacturers use combinations of convex and concave lenses. Here, a convex lens is used as the primary lens of a camera that causes distortions in the photos, which is called chromatic aberrations. Combining both concave and convex lenses eliminates these undesirable effects.