Concave Lens

A lens is an optical transmissive device that, through the process of refraction, concentrates or disperses a beam of light. A basic lens is made out of a single piece of material that is clear in nature. A compound lens, on the other hand, is made up of a number of simple lenses, or elements, that are aligned along a common axis. Plastic and glass are commonly used in the manufacture of lenses. And they’ve been polished, ground, or sculpted into the desired shapes. Unlike a prism, which simply refracts light without concentrating, a lens may focus a ray of light to form an image.

Concave Lens

In addition to making distant objects appear closer, lens might also be used to make objects that are small appear larger and objects that are fuzzy appear clear using magnifying glasses and corrective lenses.

A concave lens is one that has at least one surface that curves inwards. It is a diverging lens, which means that the rays of light that have been refracted through it are spread out. Concave lenses produce images that are upright, diminished, and virtual. Because of the divergent nature of this lens, this type of image is created. When a single beam of light passes through a concave lens, it diverges, resulting in upright, diminished, and virtual images.

A concave lens is one that is narrower in the centre than at the borders and is used to cure the problem of short-sightedness, commonly known as myopia. Pliny the Elder’s works, which span the years 23–79, mention what is widely considered to be the first usage of corrective glasses. Then we can add that, according to Pliny, Emperor Nero was said to attend a gladiatorial match while wearing an emerald, which is probably a concave shape to adjust for myopia.

Concave Lens Formula

The lens formula is used to determine the type of the image created by the concave lens, as well as its position. The formula for the lens is as follows:

1 / f=1 / v  -1 / u 

Here,

f= focal length

v= distance of the image from the centre

u= distance of the object from the centre

Similarly, the image magnification is determined by the equation,

M=hi / ho=v / u 

Here, 

 M= magnification, 

hi =height of the image

ho= height of the object.

Real and virtual images

A lens can create the following images:

1. inverted or upright (upside down compared to the object)

2. enlarged or diminished (smaller than the object)

3. real or virtual

An image that can be projected onto a screen is referred to as a real image. A virtual image always appears behind the lens.

Image formation using concave lens

Images created by concave lenses are always:

• upright

• diminished

• virtual

CASE 1: Object is at infinity

Virtual Image is formed at the focus.

The size of the image is highly diminished as compared to the object.

CASE 2: Object is placed between pole O and infinity

Virtual Image is formed between focus and pole.

The image is very small in comparison with the object.

Uses of a Concave Lens

In real life, a concave lens can be used for a variety of purposes. The following are some of these applications: –

Telescopes- Concave lenses are what you’ll find in telescopes and binoculars. Concave lenses are used in telescopes and binoculars for a variety of purposes. Concave lenses, for starters, assist in magnifying the item (Concave lenses are used before or in the eyepiece of telescopes and binoculars to help people focus more clearly). Unlike convex lenses, concave lenses do not distort the image when magnified. As a result, using concave lenses in telescopes and binoculars is critical. Concave lenses also aid in focusing clearly on the object, which is why they are utilised.

Eye-Glasses- Near-sightedness, often known as myopia, is an eye condition that makes it difficult for people to see things well at a distance. The extra length of the eyeball makes it difficult to project images of distant objects in this disease. This can be remedied with the use of concave lenses in eyeglasses. Concave lenses in eyeglasses scatter light rays a little more throughout the eye than diverging lenses, allowing the wearer to view distant things more clearly. The concave lens distributes light rays before they reach the eyeball, allowing for a clearer view of distant objects.

Lasers- Laser beams are a technology that can be found in a variety of devices. Laser beams are used in a variety of medical devices, including scanners, CD players, DVD players, and a variety of other instruments. Laser beams are typically quite focussed and must be diffused in order for an instrument to function properly. Concave lenses are used to scatter the focus of laser beams and ensure optimum operation of a gadget. Small concave lenses are commonly employed because they expand the laser beam and allow it to reach a specific location. For laser beams, concave lenses are utilized in this way.

Cameras- Convex lenses as well as concave lenses are useful in cameras. In order to improve the quality of images, concave lenses are used in conjunction with convex lenses in cameras. In a camera, using solely convex or concave lenses generates distortions and other undesired consequences. As a result, concave and convex lenses are employed in tandem to eliminate all negative effects in a camera.

Flashlights- Concave lenses are used in flashlights to magnify the light that comes out of them. The light ray passes directly through the concave lens and diverges as it passes through, giving the impression that the light is brighter. After passing through the concave lens, the light ray’s radius increases, resulting in a larger beam.

Conclusion

The lens is one of humanity’s most important inventions. Although it is impossible to establish when or how the lens was found, it is obvious that ancient people realised at some time that they could alter light using a piece of glass. Humans utilised lenses to make distant items appear closer, small objects appear larger, and hazy objects appear clear, for example (i.e., magnifying glasses and corrective lenses). Convex and Concave Lenses are two types of basic lenses that can be used to complete these tasks.

A concave lens diverges a straight light beam from the source, resulting in a decreased, upright virtual picture. It is capable of producing both real and virtual images. At Least one interior surface of concave lenses is curved. Because it is shaped round inwards at the centre and bulges outwards through the edges, causing the light to diverge, a concave lens is also known as a diverging lens. They’re used to cure myopia since they make remote objects appear smaller.