Image Formation by Lenses

What is the real image?

The image formed when rays of light meet at a certain point after reflection/refraction is real image. Real images can be displayed on screen.

What is a virtual image?

The image formed when rays of light appear to meet at particular point is called virtual image.

What is a ray diagram?

The type of diagram which helps to trace the path that light takes in order for a person to view a point on the image of an object is called a ray diagram.

What are the rules for ray tracing in lenses?

Ray tracing in lenses involves several key rules:

  1. A ray parallel to the principal axis of a converging lens passes through the focal point on the opposite side.
  2. A ray passing through the center of a lens continues straight without bending.
  3. A ray entering a converging lens through its focal point exits parallel to the principal axis. These rules help visually predict the path of light through lenses and the formation of images​.

Which lens would you use as a magnifying glass?

Convex Lens is the lens which is used in the magnifying glass.

How does the power of a lens relate to its focal length?

The power of a lens (P) is defined as the inverse of the focal length (f), given in meters. This relationship is expressed as P=1/f. For instance, a lens with a focal length of 8 cm (0.08 meters) would have a power of 12.5 diopters. The power indicates how strongly the lens converges or diverges light rays​.

What will be the focal length of a lens when it is cut along the principal axis?

There will be no change in the focal length of a lens when cut into two halves along the principal axis, because the focal length of the lens is half of the radius of curvature and radius of curvature will remain the same.

What are the basic types of lenses and how do they form images?

Lenses are categorized into two main types: convex (converging) and concave (diverging) lenses. Convex lenses cause parallel light rays to converge to a point, forming real images that can be projected onto a screen. Concave lenses, on the other hand, cause parallel light rays to diverge, making them seem as if they originate from a point; these lenses typically form virtual images that cannot be projected



Image Formation by Lenses

In optics, a ray is a geometrical representation of the light that is idealized by choosing a curve that is perpendicular to the wave fronts of actual light and points in the energy flow direction. Rays are used to represent the propagation of light through an optical system by separating the real light field into discrete rays that can be computationally carried through the system using ray-tracing techniques. This makes it possible to investigate or simulate even the most complex optical systems mathematically. Ray tracing is based on approximate solutions to Maxwell’s equations that hold true as long as light waves flow through and around objects with dimensions significantly greater than the wavelength of the light. Diffraction, for example, necessitates the study of wave optics, which is not addressed by ray or geometrical optics. Adding phase to the ray model can be used to describe wave phenomena such as interference in some instances.

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Image formed by the Convex Lens

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Image formed by Concave lens

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Image Formation by Lenses – FAQs

What is the real image?...