It’s what we see…. Light Speed light around the earth 300,000,000 m/s 3 x 10 8 m/s light around the earth 300,000,000 m/s 3 x 10 8 m/s

Its what we see

Light Speed light around the earth 300,000,000 m/s 3 x 10 8 m/s light around the earth 300,000,000 m/s 3 x 10 8 m/s

Light Speed Just over a second from the moon

Light Speed 8 minutes from the sun

Light Speed 4.2 years from Alpha Centauri! (second nearest star) Light Speed

Lightyear 170, 000 lightyears away How many years ago did it occur? How far light travels in 1 year

Plane Mirrors: The Flat Mirrors

Plane Mirrors Incident ray hits the mirror Reflected ray is the ray that bounces off The Normal is the perpendicular line from mirror Incident ray hits the mirror Reflected ray is the ray that bounces off The Normal is the perpendicular line from mirror

3 Laws of Reflection F i = r F d i to mirror = d o to mirror Apparent path of light = Actual path of light

Draw the Reflected Ray 54 1.Draw the normal 2.Measure the incident angle 3.Draw the reflected ray

Let practice! Turn to page 15 FWork together to solve #1 and #2

#1b. Headlight on a dry road

3 Laws of Reflection F i = r F d i to mirror = d o to mirror Apparent path of light = Actual path of light

Reflection Virtual Image of the nose To find an image: extend the reflected ray behind the mirror. The image is formed where the rays intersect. To find an image: extend the reflected ray behind the mirror. The image is formed where the rays intersect. dodo didi d o = object distance d i = image distance

mirror Image mirror Apparent path of light Actual path of light? Object Length of Actual Path of light = Length of Apparent path of light Length of Actual Path of light = Length of Apparent path of light

Lab part 2: Parallax real screw (behind mirror) image of screw mirror Parallax can be used to find image location Parallax makes objects appear to move when not in the same place Try it

Parallax Move head to the side If the image and real screw separate, then not at same place Try it mirror

Parallax If the two move together, they are at same place Try it mirror

Now, to the Lab Part II (pg 11)

Common Lab Shortfalls FUse Full Sentences Non-Example: FUse Full Sentences Non-Example: 4.2cm and 4.5 cm. 5% The distance from the object to the mirror is __ cm and the distance from the mirror to the image is __cm. The percent difference is __% which indicates ___________________. What is 4.2cm??? Example of a great response:

Part 2: Compare using the Percent difference

#1. Headlight on a dry road

Headlight on a dry road

1. Diffuse Reflectors

#3. Find the Object

Find the Object Image to eye 14.5 cm Object 14.5 cm Apparent path of light Actual path of light

4. Yourself in a Mirror FMinimum height of mirror?

Tip for #4 FWork backwards! Where do the rays need to reach to let everything be seen? Tip for #6 FIn order to focus you camera you must know the distance between the camera and the image

Problem 9 mirror object mirror 3.0 m 2.0 m 1.0 m A man is standing between 2 parallel mirrors looking to the left. How far away from the person are the first three images he sees?

Problem 6 mirror 2.0 m 4.5 m object image

Problem 7: 25 with the surface of the mirror ? Mirror 25 normal = incident angle 90 = + 25 90 25 = 65 = But what is the question is asking?

Curved Mirrors

Curved Mirror Vocab C = radius of the sphere the mirror was made from f = point at which rays converge F = length of the mirror to f (focal length) Ff = C/2 FConcave mirror C = radius of the sphere the mirror was made from f = point at which rays converge F = length of the mirror to f (focal length) Ff = C/2 FConcave mirror C f Center of curvature = Focal point

Image Types FVirtual images are formed by diverging light rays (example: behind a plane mirror) FReal images are formed by converging light rays FVirtual images are formed by diverging light rays (example: behind a plane mirror) FReal images are formed by converging light rays Real or Virtual?

Vocab WordPicture that reminds you of definition DefinitionWord or words that remind you of definition Sentence using word Converge Come together from different directions to eventually meet Come together Cross Eventually meet Come together Cross Eventually meet The students will converge in the cafeteria

Vocab WordPicture that reminds you of definition DefinitionWord or words that remind you of definition Sentence using word Diverge Separate and go in different directions Separate Grow apart Turn away Separate Grow apart Turn away Monkeys and Humans diverged from a common ancestor

Real vs Virtual Images FConcave Mirror FImage in front FUse a Card to see! FLight rays converge FImage is Real FConcave Mirror FImage in front FUse a Card to see! FLight rays converge FImage is Real

Real vs. Virtual Images FConcave Mirror FImage behind mirror FAppears to converge FImage is virtual FConcave Mirror FImage behind mirror FAppears to converge FImage is virtual

Real Or Virtual ? FImage behind mirror FAppears to converge FImage is virtual FImage behind mirror FAppears to converge FImage is virtual

Real Or Virtual ? FImage in front of a curved mirror FAppears to diverge FImage is real FImage in front of a curved mirror FAppears to diverge FImage is real

Let practice! Turn to page 23 FSkip pg 24 FSkip question 3 on page 27 FNormals to the surface have already been drawn as dashed lines. FSkip pg 24 FSkip question 3 on page 27 FNormals to the surface have already been drawn as dashed lines.

Concave Mirrors Cf through the focal point! Incoming Parallel rays reflect:

Concave Mirrors Cf parallel! Rays through (or from) f reflect:

Concave Mirrors Cf back through C! Rays through C reflect:

Convex Mirrors Cf away from focal point! Incoming parallel rays reflect:

Note: Only the red lines are used to locate the image Convex Mirrors Cf parallel! Rays towards focal point reflect:

Convex Mirrors Cf back away from C! Rays towards C reflect:

FChoose easiest paths F(Only need 2) FUse 3 rd to check FChoose easiest paths F(Only need 2) FUse 3 rd to check image The Image is between the Principle axis & the intersection

Finding the Image FDraw ray paths FIdentify Characteristics FDraw ray paths FIdentify Characteristics Beyond C larger inverted Real FR = Region FS = Size FO = Orientation FT = Type of Image

Now Go Make Your Own! Pages 30-33

Answers pg 31 FR = Region FS = Size FO = Orientation FT = Type of Image

Image Characteristics Concave and Convex

FConcave: (pg 32) FObject at center of Curvature FConcave: (pg 32) FObject at center of Curvature

FConcave (pg 32) FObject between C and F FConcave (pg 32) FObject between C and F

FConcave (pg 32) FObject between F and Mirror FConcave (pg 32) FObject between F and Mirror

Prior Knowledge: Lab 2 Virtual Image of the nose dodo didi d o = object distance d i = image distance + + - -

Measure object distance from the filament

Advice FRecord the object size, orientation & image position FMark & number all 11 object and image distances on your paper! F(skip recording the object and image distances, you can measure those later) FRecord the object size, orientation & image position FMark & number all 11 object and image distances on your paper! F(skip recording the object and image distances, you can measure those later) Look at the table on page 37

Your data table FImage Size: larger, smaller, or same? FImage Orientation: upright or inverted? FImage Position; behind mirror (distance will be negative) OR between mirror and object, at object, or beyond object? FImage Size: larger, smaller, or same? FImage Orientation: upright or inverted? FImage Position; behind mirror (distance will be negative) OR between mirror and object, at object, or beyond object? + + - -

How do you calculate the focal length of a curved mirror? 1/f =1/d o +1/d i f = d o d i / (d o + d i )

Lab Corrections FEarn back up to the points you lost FCorrections should be done in colored pen/pencil OR on a separate piece of paper FTurn corrections into the regrade folder FEarn back up to the points you lost FCorrections should be done in colored pen/pencil OR on a separate piece of paper FTurn corrections into the regrade folder

The Lab: Part 1 Image dodo didi d o = object distance d i = image distance

Lab Corrections FDue 1 week from the day it was due (Tuesday Tuesday) FCorrect your lab and write a note to the front telling me: 1.what you corrected 2.your original mistake FDue 1 week from the day it was due (Tuesday Tuesday) FCorrect your lab and write a note to the front telling me: 1.what you corrected 2.your original mistake NOTE: You can not earn points back by labeling the image

Use your Ray diagrams on page 30-33 to fill out the table on pg. 39 Type of mirror Object position Image PositionRelative Size OrientationType concave Mirror to focus Center of Curvature At CSameInvertedReal

Pg 39 Convex mirror Position: Size: Larger / Smaller / Same Orientation: Upright / Inverted Type: Real / Virtual Position: Size: Larger / Smaller / Same Orientation: Upright / Inverted Type: Real / Virtual

Convex mirror pg 39 Position: Size: Larger / Smaller / Same Orientation: Upright / Inverted Type: Real / Virtual Position: Size: Larger / Smaller / Same Orientation: Upright / Inverted Type: Real / Virtual Virtual Upright Smaller Behind the mirror

Mirror Equations Solving for f

Mirror Equations FMagnification FReally 3 different equations FMagnification FReally 3 different equations

Mirror Equations Image Distance Focal Length Positive negative Concave mirrors Convex mirrors In front of mirror Behind mirror object +-

Prior Knowledge: Lab 2 Virtual Image of the nose dodo didi d o = object distance d i = image distance + + - -

Lets try some examples!

1.6 A girl is using a concave makeup mirror to get ready for the prom and is 27 cm in front of the mirror. The image is 65 cm behind the mirror. a.Find the focal length of the mirror Lets go over how to approach word problems a.Find the focal length of the mirror Lets go over how to approach word problems

Solving Word Problems: GUESS 1.List your Given information (numbers you can use in eqns) make sure to label them with a variable sometimes this includes a picture 1.List your Given information (numbers you can use in eqns) make sure to label them with a variable sometimes this includes a picture

1.6 A girl is using a concave makeup mirror to get ready for the prom and is 27 cm in front of the mirror. The image is 65 cm behind the mirror. a.Find the focal length of the mirror Given:

Solving Word Problems: GUESS 2.List your Unknown this is what you are solving for! 2.List your Unknown this is what you are solving for!

1.6 A girl is using a concave makeup mirror to get ready for the prom and is 27 cm in front of the mirror. The image is 65 cm behind the mirror. a.Find the focal length of the mirror Given: f = ?

Solving Word Problems: GUESS 3.Write out the Equation you will use Write it the way you will use it 3.Write out the Equation you will use Write it the way you will use it

A girl is using a concave makeup mirror to get ready for the prom and is 27 cm in front of the mirror. The image is 65 cm behind the mirror. a.Find the focal length of the mirror Given: f = ?

Solving Word Problems: GUESS 4.Substitute: Plug your numbers into the equation Do not forget your units! 4.Substitute: Plug your numbers into the equation Do not forget your units!

Solving Word Problems: GUESS 5.Solve: Calculate and write your answer! Box it! 5.Solve: Calculate and write your answer! Box it!

A girl is using a concave makeup mirror to get ready for the prom and is 27 cm in front of the mirror. The image is 65 cm behind the mirror. b.Find the Magnification of her image. Given: M = ?

1.4 You are 2.0 m tall and stand 1.5 m in front of a mirror. You see an image of yourself that is upright and half your size. a.What type of image is it? Why? Answer: Image is virtual. Why? Because image is upright.

1.4 You are 2.0 m tall and stand 1.5 m in front of a mirror. You see an image of yourself that is upright and half your size. b.What type of mirror is it? Why? Answer: Mirror is convex. Why? Because image is smaller and virtual.

1.4 You are 2.0 m tall and stand 1.5 m in front of a mirror. You see an image of yourself that is upright and half your size. c.Find the center of curvature Given: virtual! C = ? f = ?, d i = ? Unknown : Equation: Solve: Solution:

1.4 You are 2.0 m tall and stand 1.5 m in front of a mirror. You see an image of yourself that is upright and half your size. c.Find the center of curvature solve for f c.Find the center of curvature solve for f

1.4 You are 2.0 m tall and stand 1.5 m in front of a mirror. You see an image of yourself that is upright and half your size. c.Find the center of curvature solve for C c.Find the center of curvature solve for C

1.7 A convex mirror has a center of curvature of 68 cm. If the image is located 22 cm from the mirror, where is the object? Given: Unknown: Equation: Substitute: Solve:

Object beyond C f f f f f Object at C Object between f and C Object between f and the mirror C object C Image object CC Image Concave Mirrors Image type: The focal length is positive for concave mirrors The Center of curvature is positive for concave mirrors +-

notes Object anywhere f object C Image Convex Mirrors The focal length is negative for convex mirrors fC + - Image type: The object distance is always positive because the object cannot go behind the mirror Convex only produce virtual images

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It’s what we see…. Light Speed light around the earth 300,000,000 m/s 3 x 10 8 m/s light around the earth 300,000,000 m/s 3 x 10 8 m/s