Download Plane Mirrors

Day #2 - Flat Mirrors
Honors HW: Read pp. 730-732a. and do problems 1-14 at the end of this
packet. Also, do problems 1 thru 8 all on pg. 754.
There are two types of surfaces:
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Accelerated HW: Read pp. 526-529 and do problems 1-14 (skip 10) at the
end of this packet. Also, do problems 1 thru 6 on pg. 529.
Opaque: Not allowing light to pass through it (interrupts the transmission of light).
Translucent: Allows SOME light through.
Transparent: Allowing light to pass through it (allows the transmission of light through it).
When light hits a surface, three things can happen:
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Reflection: A re-directing of light _____________ a surface (and NOT through the surface).
Refraction: The bending of light through a surface.
Absorption
Where does a ray of light come from?
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A source (light bulb, the sun, etc)
Another object (that is not creating the light ray, but rather reflects light that strikes it)
Mirror Vocabulary
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Mirror: A brightly polished “opaque” surface that reflects light in predictable ways.
Incident Ray: The ray of light that travels ____________ the mirror.
Reflected Ray: The ray of light that travels ________________ the mirror.
Normal to: _____________________.
Image: An optically formed duplicate, counterpart, or other representative reproduction of an
object, especially an optical reproduction formed by a lens or mirror.
Real Image: An image in which reflected rays ACTUALLY pass through the image itself.
These can be _________________________________.
Virtual Image: An image in which reflected rays DO NOT actually pass through the image
itself. These _________________________________.
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Plane Reflectors
Angle of incidence: angle formed between incident
ray and the __________ to the
surface.
Angle of reflection: angle formed between reflected
ray and the __________ to the
surface.
Laws of Refection:
1) _______________________________
2) _____________________________________________
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Characteristics of an image:
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_____________ (upright or inverted
)
Size (larger, smaller, or the same size as the object)
Type ( ________ vs. _________)
Perverted ( ____________ ) vs. non-perverted
Ray Diagrams
1) To find the image location of a point on the object, you must draw 2 rays from that point, draw
their reflected rays, and then find the intersection.
2) To draw the full image of a reflected object, you must repeat step #1 for EVERY point on the
object.
Or ….you need to be smart about it 
OBJECT
OBJECT
What would your eye actually see?
Image
Characteristics of an image formed by a flat mirror.
1) upright or inverted? ___________
2) larger size, smaller size, or same size? __________
3) Real or virtual? __________
4) Perverted or non-perverted? ____________
Flat Mirrors Lab
Locate/Construct the image of each object “behind” the mirror. You must use a straight-edge
and a protractor. You CANNOT find the image using GEOMETRY REFLECTIONS, but
instead have to use LIGHT RAYS (ie. RAY DIAGRAMS )
1)
2)
C
A
B
mirror
mirror
3)
4)
G
D
E
H
F
mirror
mirror
Homework: ALL answers must be written on looseleaf paper.
No answers placed on this sheet will be accepted.
1) A plane mirror produces a real / virtual (choose one) image. This is known as the image’s TYPE.
2) A plane mirror produces an upright / inverted (choose one) image. This is known as the image’s ATTITUDE.
3) A plane mirror produces a larger / smaller / same size (choose one) image. This is known as the image’s SIZE.
4) A person stands 20 cm away from a mirror. What is the distance between the person and his/her image?
5) You decide to stand 1.5 meters in front of a mirror and take a picture of yourself. To what distance should you
focus the camera in order to get a crisp, clear image?
6) In a plane mirror, is there …
a) left-right reversal? (Y or N, and explain how you know)
b) Top-bottom reversal? (Y or N, and explain how you know)
7) Write a word (any word you can think of) that will look the same when you read it normally and when you read it
in a mirror. Then, show what the word “JELLO” will look like when you read it in a mirror.
8) Specular reflection occurs when light is reflected off of shiny surfaces. In this type of reflection, light reflects
only in one direction. Diffuse reflection occurs when light reflects off rough or unpolished surfaces, resulting in
light reflecting in multiple directions at once.
a)
Which type of reflection occurs when light reflects off a lake on a bright, sunny day?
b) Which type of reflection occurs when light reflects off a trash bag?
c)
Which type of reflection occurs when light reflects off a carpet?
d) Explain in your own words how you know that light reflects off a carpet?
9) The picture at the right shows multiple images of a single golf ball that were created
using 2 flat mirrors. Explain how the mirrors are oriented relative to each other
10) A 1.8 meter tall man stands 2 meters in front of a plane mirror. What is the minimum height of the mirror that
will allow the man to view his complete image from head to foot. Assume that the man’s eyes are 12 cm below
the top of his head.
11) Why do some emergency vehicles have
written on the front? Explain.
12) Imagine that you are standing at the center of a very large clock face that is painted onto the floor of a local mall.
Someone standing one the “9” shines a laser pointer at you, and you want to reflect the laser pointer with a mirror
towards the “5”. What should the angle of incidence be in order to make this happen? What should the angle of
reflection be?
13) At some Ruby Tuesday restaurants, the salad bar has a flat mirror behind it. How large does the salad bar appear
to the casual observer?
14) Review the notes from in-class… especially the ray diagrams.