ConcepTest 35.2bMirror II You stand in front of a mirror. How
tall does the mirror have to be so that you can see yourself
entirely? 1) same as your height 2) less than your full height but
more than half your height 3) half your height 4) less than half
your height 5) any size will do
Slide 3
ConcepTest 35.2bMirror II i = r mirror only half your size
Trace the light rays from the images foot to the mirror and then to
the eye. Since we know that i = r, you need a mirror only half your
size. You stand in front of a mirror. How tall does the mirror have
to be so that you can see yourself entirely? 1) same as your height
2) less than your full height but more than half your height 3)
half your height 4) less than half your height 5) any size will
do
Slide 4
ConcepTest 35.2cMirror III Does this depend on your distance
from the mirror? 1) No. 2) Yes. 3) Depends on the mirror. 4)
Depends on the person.
Slide 5
ConcepTest 35.2cMirror III Does this depend on your distance
from the mirror? 1) No. 2) Yes. 3) Depends on the mirror. 4)
Depends on the person. The further you step back, the smaller the
incident and reflected angles will be. But the rays will still be
reflected at the same points, so the ray from the foot will still
be reflected at mid- height.
Slide 6
Thursday February 16 th 6 Light and Optics
Slide 7
TODAYS AGENDA Curved Mirrors Concave Hw: Practice B (all) p462
UPCOMING Fri: NO School Mon:Curved MirrorsConvex Tue:Problem Quiz
#1 Color and Polarization Wed:Refraction Thursday, February 16
7
Slide 8
Chapter 13 Light and Reflection
Slide 9
Formation of Images by Spherical Mirrors Spherical mirrors are
shaped like sections of a sphere, and may be reflective on either
the inside (concave) or outside (convex).
Slide 10
Formation of Images by Spherical Mirrors Rays coming from a
faraway object are effectively parallel.
Slide 11
Formation of Images by Spherical Mirrors Parallel rays striking
a spherical mirror do not all converge at exactly the same place if
the curvature of the mirror is large; this is called spherical
aberration.
Slide 12
Formation of Images by Spherical Mirrors If the curvature is
small, the focus is much more precise; the focal point is where the
rays converge.
Slide 13
Formation of Images by Spherical Mirrors Using geometry, we
find that the focal length is half the radius of curvature:
Spherical aberration can be avoided by using a parabolic reflector;
these are more difficult and expensive to make, and so are used
only when necessary, such as in research telescopes.
Slide 14
Formation of Images by Spherical Mirrors We use ray diagrams to
determine where an image will be. For mirrors, we use three key
rays, all of which begin on the object: 1. A ray parallel to the
principal axis; after reflection it passes through the focal point.
2. A ray through the focal point; after reflection it is parallel
to the principal axis. 3. A ray through the focal point; after
reflection it is parallel to the principal axis.
Slide 15
Concave Mirror Principle Focal Point Images Formed by Spherical
Mirrors R C C center of curvature = R =radius
Slide 16
Image Characteristics Images Formed by Spherical Mirrors Type:
Real or Virtual Size: Larger, Smaller, or Same (as the Object)
Orientation: Upright or Inverted do:do:always positive di:di: real
is positive; virtual is negative f:In front of mirror is positive;
Behind mirror is negative
Slide 17
Concave Mirror Images Formed by Spherical Mirrors Case #1
parallel ray focal ray central ray Image Characteristics real
smaller inverted image image found between C and f
Slide 18
Concave Mirror Images Formed by Spherical Mirrors Case #2 Image
Characteristics real same inverted image image found at the C
Slide 19
Concave Mirror Images Formed by Spherical Mirrors Case #3 Image
Characteristics real larger inverted image image found beyond C
C
Slide 20
Concave Mirror Images Formed by Spherical Mirrors Case #4 Image
Characteristics C No image Vampire case
Slide 21
Concave Mirror Images Formed by Spherical Mirrors Case #5 Image
Characteristics virtual larger upright image found behind mirror C
image Make-up case
Slide 22
Concave Mirror Light Source at the Focal Point Produces
Parallel Rays of Light Images Formed by Spherical Mirrors
Slide 23
Concave Mirror dodo didi f hoho hihi Images Formed by Spherical
Mirrors
Slide 24
Concave Mirror hoho hihi dodo didi f Images Formed by Spherical
Mirrors
Slide 25
Slide 26
Slide 27
Concave Mirror Virtual Image Images Formed by Spherical Mirrors
f
Slide 28
Concave Mirror dodo f hoho hihi didi Images Formed by Spherical
Mirrors
Slide 29
Concave Mirror f hoho hihi dodo didi Images Formed by Spherical
Mirrors M =M = Magnification M > 1 Larger M < 1 Smaller M +
Upright M - Inverted M = 1 Same
Slide 30
Images Formed by Spherical Mirrors A object is placed between a
concave mirror and its focal point. The image formed is (A) virtual
and inverted. (B) virtual and upright. (C) real and upright. (D)
real and inverted.
Slide 31
A mirror at an amusement park shows an upright image of any
person who stands 1.4 m in front of it. If the image is three times
the persons height, what is the radius of curvature? Images Formed
by Spherical Mirrors (Problem) M =M = The image characteristics
identify the case as concave #5 (larger, virtual, and upright). 3 =
= d i = -4.2 m
Slide 32
Images Formed by Spherical Mirrors If you stand in front of a
concave mirror, exactly at its focal point, (A) you will see your
image at your same height. (B) you won't see your image because
there is none. (B) you will see your image, and you will appear
smaller. (C) you will see your image and you will appear
larger.
