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Learning TargetsDescribe the difference between a real and a
virtual imageDraw ray diagrams for objects located at
various distances from concave mirrorsDraw ray diagrams for objects located at
various distances from convex mirrors
Curved vs. Flat MirrorsImages formed by curved mirrors
differ from those formed by flat mirrorsDepending on the object location, the
image could be enlarged or reduced in size
The image could also be inverted or upright
Concave Spherical MirrorsA spherical mirror with light reflecting
from its silvered, concave surface, is called a concave mirrorConcave mirrors are capable of forming
both real and virtual images
What is a Real Image???A reflected image that appears to lie in front of
the reflecting surface is called a real imageThis is in contrast to a virtual image which
appears behind the mirror. When a real image is produced, that image can
be obtained on a screen placed in front of the mirrorhttp://www.youtube.com/watch?v=KVpSCICCD9A
Ray Diagrams for Concave MirrorsThere are two rules of reflection for
concave mirrors. Any incident ray traveling parallel to the
principal axis will pass through the focal point upon reflection.
Any incident ray passing through the focal point will travel parallel to the principal axis upon reflection
Real or Virtual?Real images are formed when:
Objects are located behind the center of curvature
Objects are located at the center of curvature
Objects are between the center of curvature and the focal point
If an object is located at the focal point, the reflected rays never cross.Therefore no image is formed
Convex Spherical MirrorsThe passenger’s side mirrors on a car
bulge outward at the centerImages in this mirror are distorted near
the mirror’s edges, and the image is smaller than the object
This type of mirror is called a convex spherical mirror
Convex mirrors are also called diverging mirrors because incoming light rays diverge after reflection The resulting image is always virtual
Negative Focal LengthFor a convex mirror, the center of
curvature and the focal point are located behind the mirror.
Since the focal point is located behind the convex mirror, such a mirror is said to have a negative focal length value
Convex spherical mirrors take the objects in a large field of view and produce a small imageThis makes them well suited for providing
a complete view of a large areaThey are often placed in stores or busy
hallways
Ray Diagrams for Convex MirrorsAny incident ray traveling parallel to the
principal axis will reflect from the mirror and its extension will pass through the focal pointThis extension is represented by a dashed line
Any incident ray traveling towards a convex mirror such that its extension passes through the focal point will reflect and travel parallel to the principal axis
Image for Convex MirrorsLocated behind the convex mirror
A virtual imageAlways uprightReduced in size (i.e., smaller than
the object)
The diagram below illustrates that as the object distance is decreased:the image distance is decreased the image size is increased
So as an object approaches the mirror, its virtual image approaches the mirror and becomes larger.
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