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Uses of Convex Lens and Its Application

Uses of Convex Lens and Its Application

Vishal kumarUpdated on 02 Jul 2025, 04:48 PM IST

When the light passes through a lens and the emergent rays are converging in nature then that type of lens is known as converging lens or convex lens.
Convex lens

Uses of Convex Lens and Its Application
Uses of Convex Lens and Its Application

There are three types of convex lens

  1. Bi-convex or double convex lens
  2. Plano convex lens
  3. Concavo convex lens

In convex lens light rays get converged or come closer to each other as in the diagram above. Due to this property, convex lenses are used in different ways in different objects.

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Application of convex lens/use of lens/what are the uses of lenses/state two uses of convex lens/uses of lenses in our daily life:

  • Magnifying glass uses convex lenses .
  • Eyeglasses use convex lenses.
  • Camera uses a convex lens.
  • Telescopes use convex lenses .
  • Microscopes use convex lenses.

Convex lens used in magnifying glass:

Convex lens used in magnifying glass

Magnifying glasses are most commonly used for seeing things larger. The light from the object comes through the convex lens of the magnifying glass .The light gets converged due to the convex lens and makes the image larger in our eyes.

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Convex lens used in eyeglasses:

Convex lens used in eyeglasses

In hyperopia a human cannot be able to see things away from his sight. So, when the light rays come from an object and get through a lens then the image is formed in the retina and the farsightedness patient sees the object without any difficulty.

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Convex lens used in camera:

Convex lens used in camera

Image of convex camera

Convex lens is used in cameras not just for its focusing quality but also for its magnifying quality. Camera uses both the lenses convex and concave . There are convex lenses followed by a concave lens then a convex lens in a camera.

Convex lens used in Telescopes :

Convex lens used in Telescopes

Convex lens used in Microscope:

Convex lens used in Microscope

There are two convex lenses in a microscope. The light rays from the object come through the objective lens then through the eyepiece .Due to double refraction the object becomes larger than the actual size of the object , So, the small objects also get magnified .

Note: Magnifying glass meaning in telugu is భూతద్దం
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NCERT Physics Notes:

Frequently Asked Questions (FAQs)

Q: What is the principle behind using convex lenses in collimators?
A:
Collimators use convex lenses to convert diverging light rays into parallel rays. The principle is based on placing a point source of light at the focal point of the convex lens. Light rays emanating from this point will emerge parallel
Q: How do convex lenses help in correcting presbyopia?
A:
Presbyopia is an age-related condition where the eye's lens loses flexibility, making it difficult to focus on close objects. Convex lenses in reading glasses help correct this by converging light rays before they enter the eye, effectively doing the focusing work that the eye's lens can no longer do. This allows clear vision of nearby objects without straining the eye's focusing muscles.
Q: What is the principle behind using convex lenses in overhead projectors?
A:
Overhead projectors use a large convex lens (often a Fresnel lens) to project an enlarged image of a transparent slide onto a screen. The slide is placed just above the focal point of the lens, causing the lens to form a real, inverted, and enlarged image on the screen. Additional lenses may be used for focusing and image correction.
Q: How do convex lenses contribute to the functioning of telescopes?
A:
In refracting telescopes, convex lenses serve two main purposes:
Q: What is the concept of principal focus in a convex lens?
A:
The principal focus (or focal point) of a convex lens is the point where parallel light rays converge after passing through the lens. There are two focal points, one on each side of the lens, equidistant from the optical center. The distance from the optical center to a focal point is the focal length. Understanding the principal focus is crucial for predicting image formation and characteristics.
Q: What is the difference between a plano-convex and a biconvex lens?
A:
A plano-convex lens has one flat surface and one convex surface, while a biconvex lens has two convex surfaces. Biconvex lenses generally have shorter focal lengths and higher refractive power than plano-convex lenses of similar dimensions. Plano-convex lenses are often used in applications where light needs to be focused from a collimated beam or where minimizing certain aberrations is important.
Q: How does the refractive index of the material affect the properties of a convex lens?
A:
The refractive index of the lens material directly affects its focusing power. A higher refractive index means the lens bends light more strongly, resulting in a shorter focal length for the same lens shape. This allows for thinner, lighter lenses with the same optical power, which is particularly useful in eyeglasses. However, higher refractive index materials can also introduce more chromatic aberration.
Q: What is the concept of conjugate foci in convex lenses?
A:
Conjugate foci are pairs of points in object and image space where light from one point is focused to form an image at the other point. In a convex lens, if an object is placed at one of these points, its image will form at the conjugate point. This concept is important in understanding image formation and in designing optical systems where specific object-image relationships are required.
Q: How do convex lenses function in barcode scanners?
A:
In barcode scanners, convex lenses are used to focus laser light into a narrow beam and to collect reflected light from the barcode. The lens system typically includes:
Q: What is the significance of the f-number in convex lenses used in cameras?
A:
The f-number (or f-stop) is the ratio of the lens's focal length to its aperture diameter. It's significant because:
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