Curved mirror

A curved mirror is a mirror with a curved reflecting surface. The surface may be either convex (bulging outward) or concave (recessed inward). Most curved mirrors have surfaces that are shaped like part of a sphere, but other shapes are sometimes used in optical devices. The most common non-spherical type are parabolic reflectors, found in optical devices such as reflecting telescopes that need to image distant objects, since spherical mirror systems, like spherical lenses, suffer from spherical aberration.

Distorting mirrors are used for entertainment. They create funny and unusual shapes by stretching and squashing images. These mirrors can make you look much bigger or much smaller, depending on where you stand. Convex mirrors are often used for safety, like in stores or parking lots, because they show a wider view than flat mirrors.

Convex mirrors

A convex mirror is a curved mirror where the reflective surface bulges outward. These mirrors reflect light outward and create images that are smaller than the actual object. Because the light spreads out after reflecting, convex mirrors are not used to focus light. The images they form are virtual, meaning they appear behind the mirror and cannot be projected onto a screen.

Convex mirrors are commonly used in cars as the passenger-side mirror, often with a warning that objects in the mirror are closer than they appear. They are also found in hallways, hospitals, hotels, schools, and stores to provide a wider view around corners. These mirrors are useful for safety because they show a larger area than a flat mirror, even though objects appear smaller.

Effect on image of object's position relative to mirror focal point (convex)

Object's position (S), focal point (F)	Image	Diagram
S > F ,   S = F ,   S F,\ S=F,\ SF,\ S=F,\ S	Virtual Upright Reduced (diminished/smaller)

Concave mirrors

A concave mirror, or converging mirror, has a reflecting surface that curves inward. These mirrors reflect light to a single focal point and can show different images based on how far away the object is from the mirror. Because they gather and focus light, concave mirrors are called "converging mirrors."

Concave mirrors have many useful applications. They are used in reflecting telescopes and to magnify images for tasks like applying makeup. They help focus light in devices such as torches, headlamps, and spotlights, and are important in laser construction. They are also used in dental mirrors and in the mirror landing aid systems of modern aircraft carriers.

Effect on image of object's position relative to mirror focal point (concave)

Object's position (S), focal point (F)	Nature of Image	Diagram
S (Object between focal point and mirror)	Virtual Upright Magnified (larger)
S = F {\displaystyle S=F} (Object at focal point)	Reflected rays are parallel and never meet, so no image is formed. In the limit where S approaches F, the image distance approaches infinity, and the image can be either real or virtual and either upright or inverted depending on whether S approaches F from its left or right side.
F (Object between focus and centre of curvature)	Real image Inverted (vertically) Magnified (larger)
S = 2 F {\displaystyle S=2F} (Object at centre of curvature)	Real image Inverted (vertically) Same size Image formed at centre of curvature
S > 2 F {\displaystyle S>2F} (Object beyond centre of curvature)	Real image Inverted (vertically) Reduced (diminished/smaller) As the distance of the object increases, the image asymptotically approaches the focal point In the limit where S approaches infinity, the image size approaches zero as the image approaches F

Mirror shape

Most curved mirrors are shaped like part of a sphere because this is the simplest way to make them and works well for many uses. However, spherical mirrors can sometimes cause blurry images because the light rays don’t all meet at one point after reflecting. For better focus, especially with light coming from far away, a parabolic reflector can gather the light into a tighter spot. A toroidal reflector is a special type of parabolic mirror that has different focusing distances depending on the angle.

Analysis

The Gaussian mirror equation connects the distance of an object from a mirror, the distance of the image formed, and the mirror's focal length. For convex mirrors, images always appear virtual and behind the mirror. For concave mirrors, images can be real or virtual depending on the object's distance from the mirror compared to the focal length.

Ray tracing is another way to find where an image forms. By drawing rays from the object to the mirror and following reflection rules, you can determine the image's location and size. One ray goes to the mirror's surface vertex and reflects at the same angle. Another ray parallel to the axis reflects through the focal point. Where these rays meet shows where the image appears.