In
optics
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultra ...
, an erect image is one that appears right-side up. An
image
An image is a visual representation of something. It can be two-dimensional, three-dimensional, or somehow otherwise feed into the visual system to convey information. An image can be an artifact, such as a photograph or other two-dimensio ...
is formed when
rays from a point on the original object meet again after passing through an optical system. In an erect image, directions are the same as those in the object, in contrast to an inverted image. It is one of the properties of images formed in a
plane mirror
A plane mirror is a mirror with a flat ( planar) reflective surface. For light rays striking a plane mirror, the angle of reflection equals the angle of incidence. The angle of the incidence is the angle between the incident ray and the surfac ...
.
Some
telescopes
A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to obser ...
and other devices such as the
camera obscura
A camera obscura (; ) is a darkened room with a small hole or lens at one side through which an image is projected onto a wall or table opposite the hole.
''Camera obscura'' can also refer to analogous constructions such as a box or tent in ...
present an inverted image on the viewing surface.
Mirror
A mirror or looking glass is an object that Reflection (physics), reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the ...
s and
compound prism elements can be used to achieve an erect image instead.
Optics
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