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Overview
A mirror is a surface designed to reflect light in an organized way. Plane mirrors form familiar upright virtual images, while curved mirrors can converge or diverge light and create a variety of image types. Mirrors are central to optics, imaging, telescopes, safety devices, instruments, and everyday vision.
Plane Mirrors
A plane mirror is flat. It forms a virtual image that appears behind the mirror at the same distance the object is in front of it. The image is upright and the same size as the object.
Concave Mirrors
A concave mirror curves inward and can converge reflected light toward a focal point. It can form real or virtual images depending on the object position.
Convex Mirrors
A convex mirror curves outward and spreads reflected rays. It forms virtual, upright, reduced images and gives a wide field of view.
Focal Point
For a curved mirror, the focal point is the point where rays parallel to the principal axis converge or appear to diverge after reflection.
Real and Virtual Images
A real image forms where reflected rays actually meet and can be projected. A virtual image appears to come from a location behind the mirror where rays only appear to originate.
Ray Diagrams
Ray diagrams help predict image location, size, orientation, and type. They use selected rays whose reflection behavior is easy to trace.
Mirror Equation
The mirror equation relates object distance, image distance, and focal length in ideal mirror models. It is useful for quantitative image problems.
Applications
Mirrors are used in bathrooms, vehicles, telescopes, microscopes, lasers, periscopes, solar concentrators, lighting systems, and optical instruments.
Common Mistakes
A common mistake is thinking all mirror images are the same kind. Plane, concave, and convex mirrors behave differently and can produce different image types.
Why This Matters in Physics
Mirrors connect reflection to image formation and are essential for optics, astronomy, engineering, safety systems, and instrument design.