Learn about thin lens formula which is an equation that shows the relation between focal length, object distance and image distance of a lens.

Lens formulaClass 10

Consider a thin lens with optical center O, having focal length f. An object of height AB (h) is placed beyond 2F of the lens. Suppose two light rays pass through the object to form a smaller image of height A’B’ (h’) between F and 2F at the other side of the lens.

Magnification oflens formula

Lens formula, often known as the Thin Lens Formula, is a mathematical formula that links focal length, object distance and image distance. The lens formula essentially allows you to determine the focal length of various lenses by plugging in known object and picture distances into the calculation. That is why the formula is also known as the focal length formula.

While studying lenses, all the distances are measured from the optical centre of the lens. For convenience in calculation purposes, all distances in the same direction of the incident ray are taken positive and all distances in the opposite direction of the incident ray are taken negative. This is called sign convention.

Lens formulacalculator

The ratio of the height of the image created to the height of the object is the magnification of a lens. We can deduce from the ray diagram above that,

Are you aware that focal length and light ray bending are linked? As the focal length decreases, the number of light bends rises. As a result, a lens’ focal length and intensity are inversely related. A short focal range helps to boost optical strength. So now, let’s start with some fundamental principles about lens power.

(All distances opposite to the direction of the incident ray are taken negative.We can determine the power of a lens and its magnification using lens formula.)

Lensequation

The lens formula is used to determine any of the three quantities of a lens, focal length, object distance, and image distance.

Consider a light ray is incident upon a curved surface to be refracted from a medium of refractive index 1 to a medium of refractive index  2 .

The lens formula is used to determine any of the three quantities of a lens, focal length, object distance, and image distance.

Hence, another definition of magnification is the ratio between image distance and the object distance. The magnification has no unit.

Cameras, binoculars and telescopes all employ lenses. Magnifying glasses must be known to you. A single convex lens with a frame makes up a simple magnifying glass. Lenses such as spectacles and contact lenses are used to correct vision problems such as hypermetropia (long-sightedness) and myopia (nearsightedness) (short-sightedness).

Optical lens

While studying lenses, all the distances are measured from the optical centre of the lens. For convenience in calculation purposes, all distances in the same direction of the incident ray are taken positive and all distances in the opposite direction of the incident ray are taken negative. This is called sign convention.

The power of a lens is one of the most exciting concepts in ray optics. Simply put, in ray optics, a lens’s ability to bend light is its strength. The power of a lens is proportionate to its capacity to refract light that travels through it. A convex lens’ converging ability is determined by its strength.

Glasses, contact lenses, telescopes, binoculars, magnifying glasses, and pretty much any optical equipment employ lenses. It emphasises the significance of lenses and the importance of determining the focal length of various lenses for varied purposes. Optical experts devised a lens formula, which was primarily used to determine the focal length of lenses. We can deduce from the preceding explanation that:The relationship between the focal length, object distance, and image distance of the lens is shown in the lens formula. If we know the other two variables of the lens, it will be easier to figure out the unknown variable. It is only suitable for ultra-thin lenses. The good news is that all we see in our daily lives is through thin glasses. The lens formula also aids in determining the lens’ magnification and power. The thin lens formula is written as 1/f = 1/v – 1/u. The formula of a lens’s power is P = 1/ f and magnification is given by M = v/u.

Lenses are curved, transparent objects that refract light. Convex lenses (bulging outward, converging light rays) and concave lenses (bulging inward, diverging light rays) are two types of lenses (depressed inwards, diverging light rays).