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Concave Mirror

Definition: What is Concave Mirror?

A concave mirror is a curved mirror that forms a part of a sphere and designed in such a way that rays of light falling on its shiny surface converge upon reflection. Hence, it is also called a converging mirror. A concave mirror produces both real and virtual images, which can be upright or inverted. The size of the image can be bigger or smaller than the object. The nature, size, and position of the image depend on the position of the object.

Concave Mirror

Ray Diagram for Concave Mirror

Terms Used in Concave Mirror Imaging

  1. Incident ray – The ray of light that is incident on the surface
  2. Reflected ray – The ray of light that is reflected from the surface
  3. Center of curvature – The center of the sphere from which the concave mirror has been constructed
  4. Radius of curvature – The radius of the sphere from which the concave mirror has been constructed
  5. Pole – The mid-point of the concave mirror
  6. Principal axis – An imaginary line that connects the pole and the center of curvature
  7. Focus – A point on the principal axis where rays of light that are parallel to the axis converges after reflection
  8. Focal length – The distance between the pole and the focus and is one-half of the radius of curvature
  9. Object distance – The distance between the object and the pole
  10. Image distance – The distance between the image and the pole
Concave Mirror Ray Diagram

Applications of Concave Mirror

  • In torchlight, headlamp, vehicle headlight, searchlight, and lighthouse, where a beam of light is converged to a certain point thus giving a better focus
  • As vanity mirrors for facial makeup and as shaving mirrors for shaving
  • In solar ovens to collect an enormous amount of solar energy and concentrate it at a point for heating and cooking
  • By dentist to examine teeth and ENT specialist to observe a magnified image of the ear canal
  • In an electron microscope, astronomical telescope, and visual bomb detectors

Difference between Concave Mirror and Convex Mirror

Concave Mirror vs. Convex Mirror

Property Concave Mirror Convex Mirror
Other names Converging mirror Diverging mirror, fish-eye mirror
Reflecting surface Curved inwards Curved outwards
Center of curvature Lies on the same side of the reflecting surface Lies on the opposite side of the reflecting surface
Focus and focal length Lies in front of the mirror and focal length is positive Lies behind the mirror and focal length is negative
Image Real and inverted, except when the object is placed between the pole and the focus. In that case, the image is virtual, upright, and enlarged. Virtual, upright, and diminished
Image size Can be smaller, equal to, and bigger than the object depending on the position of the object Smaller than the size of the object
Image position Can be anywhere on principle axis depending on the position of the object Always within the focus
Image projection Only real image can be projected on a screen Cannot be projected on a screen
Uses and applications Reflecting telescope, headlamp, searchlight, and torchlight Side view mirrors in vehicles and as security mirrors in grocery stores and supermarkets

Article was last reviewed on Tuesday, July 7, 2020

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