18.1 Mirrors
Katie Hanna
Mirrors
 Mirrors are the oldest optical instruments.
 Prehistoric humans saw their faces
reflected in the quiet water of lakes or
ponds.
 Almost 4,000 years ago, Egyptians used
polished metal mirrors to view their
images.
Hall of Mirrors Versailles. N.d. Visiting DC. Web. 1 Mar. 2011.
<http://www.visitingdc.com/paris/hall-of-mirrorsversailles.asp>.
Jean Foucault
 Sharp, well-defined reflected images were
not possible until 1857, when Jean
Foucault, a French scientist, developed a
method of coating glass with silver.
Jean Foucault. N.d. Knowledge Rush. Web. 1 Mar. 2011.
<http://www.knowledgerush.com/kr/encyclo
pedia/Leon_Foucault/>.
Objects and Images in Plane
Mirrors
Plane Mirrors
 A flat, smooth surface from which light is
reflected by regular reflection rather than
by diffuse reflection.
 Bathroom Mirrors.
 Regular Reflection.
Plane Mirror. N.d. EdInformatics. EdInformatics
Org., n.d. Web. 1 Mar. 2011.
<http://www.edinformatics.com/in
ventions_inventors/mirror.htm>.
Objects
 A source of spreading, or diverging light
rays.
 Every point on an object is a source of
diverging light rays.
 Anything reflected in a
mirror.
Object in a Mirror. N.d. Physics Problems to Challenge
Understanding. Donald Simanek, n.d.
Web. 1 Mar. 2011.
<http://www.lhup.edu/~dsimanek/scenario/
insight.htm>.
Images
 An image is a reproduction of an image
formed with mirrors or lenses.
 The reflected image of an object.
Image in a Mirror. N.d. Physics 20. Physics, n.d.
Web. 2 Mar. 2011.
<http://www.sasked.gov.sk.ca/docs/
physics/u3b22phy.html>.
Virtual Images
 A reflection in a normal mirror is actually a
virtual image because the light rays do not
actually converge on that point.
Virtual Image. N.d. SMU Physics and Astronomy
Demonstrations. SMU, n.d. Web.
2 Mar. 2011.
<http://www.ap.smu.ca/demos/
index.php?option=com_content
view=article&id=122&Itemid=85
Erect Image
 If the image and object are pointing in the
same direction as each other, it is an erect
image.
More Help
 Mirrors Explained
 http://library.thinkquest.org/27356/p_mirror
s.htm
 http://www.pa.msu.edu/courses/2000fall/P
HY232/lectures/lenses/images.html
 http://www.physicsclassroom.com/class/re
fln/u13l4a.cfm
Concave Mirrors
Concave Mirror
 A concave mirror reflects light from its
inner (“caved in”) surface.
 Makeup mirror, Inside of a spoon
Spoon. N.d. Smooth Harold. Blake Snow, n.d.
Web. 2 Mar. 2011.
<http://www.smoothharold.co
m/smoothharolds-top-10
spoon-songs/>.
Concave Mirror
Image formation by a concave mirror. N.d. Spherical Mirrors. Richard
Fitzpatrick, n.d. Web. 2 Mar. 2011. <http://farside.ph.utexas.edu/
teaching/302l/lectures/node136.html>.
Spherical Concave Mirror
 In a spherical concave mirror, the mirror is
part of the inner surface of a hollow
sphere.
Spherical aberration in a concave mirror . N.d. Spherical Mirrors. Richard
Fitzpatrick, n.d. Web. 2 Mar. 2011. <http://farside.ph.utexas.edu/
teaching/302l/lectures/node136.html>.
Principal Axis
 The principal axis is the straight line
perpendicular to the surface of a mirror at
its center.
Focal Point
 The focal point is the point on a mirror
where parallel rays meet.
Focal point. N.d. Pirates and Revolutionaries. N.p., n.d. Web. 2 Mar. 2011.
<http://piratesandrevolutionaries.blogspot.com/2009/07/
deleuzes-dance-iii-wonders-of-phenomena.html>.
Focal Length
 The focal length is the distance from the
focal point to the mirror along the principal
axis.
Real Image
 A real image is an image that rays actually
converge and pass through.
 Can be seen on a piece of paper or
projected onto a screen.
Lens/Mirror Equation
 You can use geometry to relate the focal
length of the mirror, f, to the distance from
the object to the mirror, do, and to the
distance from the image to the mirror, di.
Lens/Mirror Equation. N.d. Online Physics Lab. PhysicsLAB, n.d. Web. 3 Mar.
2011. <http://dev.physicslab.org/
Document.aspx?doctype=3&filename=GeometricOptics_MirrorEquation.xml>.
How to Solve the Equation
 To solve the equation:
 Use the least common denominator, dido.
 Take the reciprocal of both sides.
Lens/Mirror Equation 2. N.d. Online Physics Lab. PhysicsLAB, n.d. Web. 3 Mar.
2011. <http://dev.physicslab.org/
Document.aspx?doctype=3&filename=GeometricOptics_MirrorEquation.xml>.
Magnification
 Magnification, m, is the ratio of the size of
the image, hi, to the size of the object, ho.
m=
Magnification Equation. N.d. Physics Study Guide. N.p., n.d. Web. 3 Mar. 2011.
<http://whs.wsd.wednet.edu/Faculty/Busse/MathHomePage/busseclasses/physics/
studyguides/chapter14/Chapter14StudyGuide2010.html>.
Spherical Aberration
 The image formed by parallel rays in a large
spherical mirror is a disk, not a point. This effect
is called spherical aberration.
 A parabolic mirror has
no spherical aberration
because all parallel
rays are reflected to a
single spot.
Spherical Aberration. N.d. Refracting vs Reflecting. N.p., n.d.
Web. 3 Mar. 2011.
<http://wisp.physics.wisc.edu/astro104/lecture
7/lec7h.html>.
Convex Mirrors
Convex Mirrors
 A convex mirror is a spherical mirror that
reflects light from its outer surface.
 Wide-angle mirrors for safety and security.
A Wide Angle Photo Of A Wide Angle Mirror Through A
Wide Angle Mirror. N.d. Flickr. Yahoo!
Inc., n.d. Web. 2 Mar. 2011.
<http://www.flickr.com/photos/218977
7@N00/2764057556>.
Works Cited
 Colwell, Catharine H., comp. "Mirror Equation.“
Online Physics Lab. PhysicsLAB, n.d. Web.
26 Feb. 2011.
<http://dev.physicslab.org/Document.as
px?doctype=3&filename=GeometricOpt
ics_MirrorEquation.xml>.
 Kirkland, Kyle, and Sean M. Grady. "mirrors and
lenses in optics." Science Online. Facts On
File, Inc. Web. 25 Feb. 2011.
<http://www.fofweb.com/activelink2.asp?Item
ID=WE40&SID=5&iPin=STIFO0005&Single
Record=True>.
 Zitzewitz, Paul W. Physics Principles and
Problems. New York: Glencoe, 2002. Print.