Virtual image

Plane mirror

Lens3b

Virtual Image

A virtual image is a concept in optics and physics, referring to an image formed when the outgoing rays from a point on an object diverge. Unlike a real image, a virtual image cannot be projected onto a screen, as it appears to be located behind the optical device (such as a lens or mirror) that generates it. Virtual images are formed by the apparent divergence of rays; because the rays do not actually originate from the image location, these images cannot be captured directly onto a physical medium. They are, however, visible to an observer looking through or into the optical device.

Formation

Virtual images are typically formed by concave lenses and convex mirrors. In the case of a concave lens, parallel rays of light are spread out (diverge) after passing through the lens. The rays appear to emanate from a common point behind the lens. Similarly, a convex mirror causes reflected rays to diverge, and to an observer, these rays appear to originate from a point behind the mirror.

Characteristics

• Location: Virtual images appear to be located on the opposite side of the lens or mirror from where the rays originated.
• Orientation: They are upright, maintaining the same orientation as the object.
• Type: Cannot be captured on a screen, as they do not involve the convergence of light rays at the image location.
• Visibility: Can be seen by looking through the optical device that creates them.

Applications

Virtual images have various applications in optical devices and instruments. For example:

• In eyeglasses and contact lenses, especially those designed to correct farsightedness, where they help to focus light correctly on the retina.
• Magnifying glasses and microscopes use lenses that produce virtual images, magnifying the object being viewed.
• Periscopes and binoculars often employ the principle of virtual images to allow users to see objects that are not directly in line of sight.
• Holography and certain types of optical illusions (like the mirage) rely on the properties of virtual images to create three-dimensional effects.

Comparison with Real Images

Unlike virtual images, real images are formed when light rays converge and can be projected onto a screen. Real images are inverted, meaning they appear upside down and reversed from left to right, in contrast to the upright orientation of virtual images. Real images are formed by convex lenses and concave mirrors under certain conditions.

See Also

• Lens (optics)
• Mirror
• Optical device
• Image formation