Convex Lens - Definition, Types, Uses, FAQs

Define Convex lens.

Convex lens Definition and Convex meaning: The convex lens converges light rays that travel parallel to its primary axis (i.e. converges incident rays towards the principal axis) and is comparatively thick in the middle and thin at the lower and upper edges. Convex lens is also known as converging lens because it converges parallel beam of light on point called principal focus. A convex lens can generally converge a beam of parallel rays to point on the other side of the lens. This point is known as the lens' focus, and the focal length is the distance between it and the Optical Centre of the beam. An approximate equation connects radius of curvature R1 and R2 of spherical surfaces as well as focal length of lens ‘f'.

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For a Mathematical Equation, use the following formula:

1/f = (n–1)(1/R₁–1/R₂)

The refractive index of the material is denoted by n.

R₁ and R₂ are the curvature radii.

R₁ refers to the surface that is closest to the light source.

R₂ refers to the surface that is far away from the light source.

The focal length of a Double Convex lens is longer due to the presence of a second curved surface. Double Convex lenses are popular because many optical systems demand larger focal lengths.

Why is a convex lens called a Converging lens?

Because it converges a parallel beam of light on a point called the principal focus, a convex lens is called a converging lens.

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Magnification of Convex lens:

Convex lens magnification is defined as the ratio of picture height to object height. A magnification of 2 means that the picture is twice the size of the object; whereas a magnification of 1 means that the image is the same size as the object. When the magnification is positive, the picture is vertical in relation to the object (virtual image). The picture is reversed in comparison to the object when magnification is negative (real image).

Types of convex lenses:

Convex lenses come in a variety of shapes and sizes.

1. Plano-convex lens: This lens has a plano-convex shape.

It is curled outwards on one side and flat on the other. Positive focal length elements with one spherical and one flat surface are used. These lenses are made for non-critical applications that require unlimited parallel light.. It's used in pharmaceuticals, defence, and robots, among other things.

2. Double Convex lens:

From both sides, it curves outwards. The Biconvex lens, or just convex, is another name for it. Plano-convex lenses of identical diameter and surface radius have a lower focal length. Longer focal lengths are required by so many optical devices. As a result, double convex lenses are chosen. It is used in projectors, monoculars, telescopes, and cameras, among other things. It served as a virtual image for the human eye and a real image for photography, as well as an optical sensor and a burner for glass.

3. Concave-Convex lenses:

From one side, it curves inwards, while from the other, it curves outwards. It can be used to compensate for other lenses' spherical aberrations. Its purpose is to control the laser beam. A concave-convex lens or meniscus is a combination of lenses with one convex lens along with one concave lens side.

Convex lens's image formation:

1. The real image is produced by the convex lens at the focus when an object is positioned at infinity. The image is a fraction of the size of the actual object.
2. The real image is produced by the convex lens, between the center of curvature and the focus when an object is positioned behind the centre of curvature. When compared to the size of the thing, the image is the same size.
3. The real picture of an object is produced by the convex lens at the other center of curvature when it is at the center of curvature. When compared to the size of the object, the image is the same size.
4. When an object is placed between the center of curvature and the focus of the convex lens then, the real image is created behind it. The image is much larger than the size object.
5. A real image is produced at infinity when an object is put at the focus of the convex lens. The image is much larger than the actual object.
6. A virtual image is produced when an object is placed between the focus and the pole of the convex lens. The image is significantly larger than the actual object.

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Convex lens: Real Image and Virtual Image

Real Image:

When an object is positioned at a distance of more than one focal length from the lens, a convex lens can be utilised to provide a genuine/real image. It can be projected in front of the lens and captured on a screen. It's what you'd find in a movie theatre, along with a projector and other equipment.

Imaginary Image:

If the item is in front of the focal point, a convex lens will produce a virtual picture. It is utilised to provide crisp images in eyewear.

Uses of Convex lenses

1. For hyperopia correction, a convex lens is used. Farsightedness, also known as hypermetropy, is the inability to see distant objects clearly while also having difficulty focusing on close objects.
2. In microscopes and magnifying glasses, a convex lens converges all incoming light rays to a single point.
3. In camera systems, the convex lens is used. Because it focuses light and generates a clear and crisp image, it is utilised in cameras.
4. The projector also uses a convex lens, also called a converging lens. A projector is used to create an enlarged, real, and inverted image of an item that is slightly beyond the focus length of a thin convex lens and can be projected onto a screen.
5. A magnifying glass is one of the most straightforward and simplest uses of a convex lens. When light rays enter the magnifying glass's convex lens, they focus on a certain focal point in front of the lens's center.

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