Created By : Naaz Fatima

Reviewed By : Phani Ponnapalli

Last Updated : Apr 10, 2023

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Image Distance(y):
Object Distance(x):

What is meant by Thin Lens?

If the thickness of a lens is negligible in comparison to radius of curvature then it is said to be a thin lens.

Thin Lens Equation

If we place an object near the lens we get the image somewhere else. However, the position, size and orinetation of the image depends on two factors namely focal length of the lens, position of the original object. Typical thin lens formula describes the relation between focal lens of the object, distance of the object, distance of the image and is given by the equation

1/x + 1/y = 1/f

  • Where f is the focal length
  • x is the distance between the object and center of lens
  • y is the distance between image and center of lens

There are two types of lenses namely convex and concave lenses. We can differentiate between them by observing the focal length. Lenses having focal length f >0 is called converging lens and focal length f<0 are called diverging lenses. If the image distance is positive i.e. y>0 then it appears on the other side of the lens and is known as real image. if the image distance y<0, it appears on the same side of the lens and we call it a virtual image.

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Magnification Lens Equation

We can estimate the magnification of created image too easily using the formula M = |y|/x where y is the distance of image and x is the distance of the object. In general, magnification value should be psitive and that's the reason we have chosen absolute value of y which can be either positive or negative.

Images in Converging Lens

Let us consider five different scenarios of converging lens(f>0) and see the image orientation and all. They are as under

  • If x>2f, image would be real(y>0) and looks diminished(M<1)
  • If x = 2f, image would be real(y>0) and is same as the size of the object(M=1)
  • If 2f > x > f image is real(y>0) and appears magnified(M>1)
  • If x = f, image will not appear properly and (y -> Infinity)
  • If x < f, image is virtual(y<0) and maginified(M>1)

FAQs on Thin Lens Equation Calculator

1. What is a Thin Lens?

If the thickness of the lens is negligible in comparison to the radius of curvature then it is called a thin lens.

2. What is the Thin Lens Formula?

Thin Lens Equation is given by the equation 1/x + 1/y = 1/f

3. What is the difference between thin and thick lenses?

A thick lens is more curved and has smaller radius of curvature. On the other hand, thin lens is less curved and has larger radius of curvature.

4. What does f stands for in Thin Lens Equation?

f stands for focal length in Thin Lens Equation.