Lecture 2: Reflection of Light: Mirrors Ch 25

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Lecture 2 Reflection of Light Mirrors (Ch
25)Refraction of Light Lenses (Ch 26)
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Light - Electromagnetic Wave

• Wavefronts
• Rays
• Plane waves

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Reflection of Light
The incident ray, the reflected ray, and the
normal to the surface all lie in the same plane,
and the angle of reflection equals the angle of
incidence
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Formation of images by a plane mirror
The image is upright. The image is the same size
as you are. The image is located as far behind
the mirror as you are in front of it.
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Spherical Mirror
CONCAVE Mirror
Focal length of concave mirror ½ R
Spherical Aberration
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Spherical Mirror
CONVEX mirror
Concave Solar Concentrators
Focal length of convex mirror - ½ R
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Formation of image by CONCAVE mirror
Ray 1, This ray is initially parallel to the
principal axis and, therefore, passes through the
focal point F after reflection from the
mirror. Ray 2.This ray initially passes through
the focal point F and is reflected parallel to
the principal axis. Ray 2 is analogous to ray 1
except that the reflected, rather than the
incident, ray is parallel to the principal
axis. Ray 3.This ray travels along a line that
passes through the center of curvature C and
follows a radius of the spherical mirror as a
result, the ray strikes the mirror
perpendicularly and reflects back on itself.
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Formation of image by CONCAVE mirror
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Formation of image by CONVEX mirror
Ray 1,This ray is initially parallel to the
principal axis and, therefore, appears to
originate from the focal point F after reflection
from the mirror. Ray 2.This ray heads toward F,
emerging parallel to the principal axis after
reflection. Ray 2 is analogous to ray 1, except
that the reflected, rather than the incident, ray
is parallel to the principal axis. Ray 3.This ray
travels toward the center of curvature C as a
result, the ray strikes the mirror
perpendicularly and reflects back on itself.
An object placed in front of a convex mirror
always produces a virtual image behind the
mirror. The virtual image is reduced in size and
upright.
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The Mirror Equation and Magnification
F Focal length do Object distance di Image
distance m Magnification
Concave mirror The image distance is a positive
quantity, as are the object distance and the
focal length. If the Image is formed behind the
mirror, the image distance is negative.
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Summary of Sign Conventions for Spherical
Mirrors Focal length f is for a concave
mirror. f is - for a convex mirror. Object
distance do is if the object is in front of
the mirror (real object). do is - if the object
is behind the mirror (virtual object). Image
distance di is if the image is in front of
the mirror (real image). di is - if the image is
behind the mirror (virtual image).
Magnification m is for an image that is
upright with respect to the object. m is - for
an image that is inverted with respect to the
object.
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Refraction and Snells Law
Index of Refraction n v c/n, where c speed
of light in vacuum
When light travels from a material with
refractive index n1 into a material with
refractive index n2, the refracted ray, the
incident ray, and the normal to the interface
between the materials all lie in the same plane.
The angle of refraction is related to the angle
of incidence by
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More on refraction and its effects
Apparent depth d d (n2/n1)
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Snells Law Derivation
http//www.physics.northwestern.edu/vpl/optics/sne
ll.htm l
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Total Internal Reflection
Optical Fiber
Sparkle of Diamond
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Dispersion
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Lenses
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Formation of Image by Lenses
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Thin Lens Equation and Magnification
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Summary of Sign Conventions for Lenses Focal
length f is for a converging lens.f is - for
a diverging lens. Object distancedo is if
the object is to the left of the lens (real
object), as is usual.do is - if the object is to
the right of the lens (virtual object). Image
distancedi is for an image (real) formed to
the right of the lens by a real object.di is -
for an image (virtual) formed to the left of the
lens by a real object. Magnificationm is for
an image that is upright with respect to the
object.m is - for an image that is inverted with
respect to the object.
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Lenses in Combination
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The Human Eye
Light travels through five different refractive
index mediums before reaching the retina!
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Near and Farsightedness
Lasik How does it work?
http//www.sankaranethralaya.org/lasik_work.htm
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The Compound Microscope
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The Telescope