12.2 Reflection of light How do you look in others’ eyes?

Slides:



Advertisements
Similar presentations
Laws of Reflection From the Activity you performed, when you shine an incident light ray at a plane mirror, the light is reflected off the mirror and forms.
Advertisements

Chapter 17 Geometrical Optics.
Reflection Objectives:
Why can the image of the building be seen inside the plane mirror ? P.43.
14-2 Flat mirrors Distinguish between specular and diffuse reflection of light. Apply the law of reflection for flat mirrors Describe the nature of image.
Introduction to Mirrors
The bouncing off of light as it hits a surface
Optics 光學 1. Reflection of Light.
Reflection Light incident upon a boundary between
Images on a Plane Mirror
Rays and Plane Mirrors The line of particles on the crest of a wave is called a wave front Huygen’s Principle = a wave front can be divided into point.
Ray Diagrams & Reflection Images in plane mirrors
Copyright © 2009 Pearson Education, Inc. Chapter 32 Light: Reflection and Refraction.
Plane Mirrors SNC2P – Optics. Plane Mirrors Mirrors reflect in predictable ways. As the angle of incidence (i) increases, the angle of reflection (r)
Image Characteristics
Reflections in a Plane Mirror
Distinguish between specular and diffuse reflection of light. Apply the law of reflection for flat mirrors. Describe the nature of images formed by flat.
Reflection: What is it? Reflection occurs when light bounces off an object. Reflection allow our eyes to see the world around us!
Lesson 6. A village in Italy does not receive sunlight from November 11 th – February 2 nd because it is in a valley.
Discover PHYSICS for GCE ‘O’ Level Science
Ray Model A useful model under certain circumstances to explain image formation. Ray Model: Light travels in straight-line paths, called rays, in ALL.
Mirrors & Reflection.
High School by SSL Technologies Physics Ex-47 Click THE LAW OF REFLECTION When light strikes a surface and is reflected, it changes direction. The direction.
Chapter 17: Reflection & Mirrors Honors Physics Bloom High School Mr. Barry Latham.
Reflection Regular reflection occurs when parallel light rays strike a smooth surface and reflect in the same direction. Diffuse reflection occurs when.
Unit 3: Light.  Plane mirror- a smooth reflecting surface  Virtual image- images formed by a plane mirror. CANNOT be projected onto a screen  Real.
OBJECTIVE At the end of this lesson, you should be able to: –Describe the characteristic of the image formed by reflection of light. –Solve problem involving.
Science Olympiad Optics Color and Shadows Optics.
Geometric Optics. Uses wave model of light to explain properties such as reflection and refraction Assumptions of geometric optics - light travels in.
1. Two long straight wires carry identical currents in opposite directions, as shown. At the point labeled A, is the direction of the magnetic field left,
SECONDARY 3 PHYSICS For E-Learning, please read slides 1 to 15
Line Ray Beam the paths along which light energy travels a bundle of light rays.
Do Now What is the color of a light wave with a frequency of 5.65 x Hz?
Light very often travels in straight lines. We represent light using rays, which are straight lines emanating from an object. This is an idealization,
Plane Mirrors.
Reflection and Light Flat Mirrors.
LIGHT Principles of Physics. It is impossible to see the actual wave shape (crests and troughs, etc) of a light wave Instead we draw straight lines, called.
Text book pages Do 7.1 – 7.3 in your workbooks
A Brief Look at LIGHT.
PW2 - Reflection.  The angle of incidence is equal to the angle of reflection.  The incident ray, reflected ray, and normal all line in the same plane.
GİZEM SENA DÜNDAR ÖZNUR HANCI MUHAMMED DOĞAN.  A ray of light is reflected on a plane mirror. mirror This is an example of reflection of light.
Reflection and Refraction of Light
Flat Mirrors And the Law of Reflection. Types of Reflection There are two main ways in which light reflects. Diffuse Reflection is caused by light hitting.
Reflection & Mirrors. Reflection The turning back of an electromagnetic wave (light ray) at the surface of a substance. The turning back of an electromagnetic.
The amount of reflection depends on how different the media are.
Notes on Chapter 29 Reflection & Refraction
Reflections in a Plane Mirror
Ray Model A useful model under certain circumstances to explain image formation. Ray Model: Light travels in straight-line paths, called rays, in ALL.
Physics.
Laws of Reflection and Plane Mirror Images
Why we see images in mirrors Or… The angle of reflection is equal to the angle of incidence.
Light: Geometric Optics. The Ray Model of Light The ray model of light assumes that light travels in straight-line path called rays.
Plane Reflection – Learning Outcomes  Demonstrate the laws of reflection.  Discuss images formed in plane mirrors.  Differentiate between real and virtual.
Image Characteristics Worksheet Answers. Location The object is the same distance to the mirror as the image is to the mirror. Attitude/ Orientation The.
1.3 Images formed by a plane mirror
Circular wave fronts Plane wave Fronts Produced in a Ripple Tank.
As regards the formation of an image by an optical system such as a plane mirror, what will serve as an object? a) An emitter of light, such as, a candle.
Reflection of light. 1You can have a view of yourself if you look into a mirror. calm water surface. a piece of shiny metal wall. a piece of window glass.
Law of Reflection & Plane Mirrors
Chapter 24 Geometric Optics
Reflection.
Light and Sight.
Ray Diagrams & Reflection Images in plane mirrors
Law of Reflection θ(i) = θ(r) θ(i) θ(r)
Reflection and Light Flat Mirrors.
Reflection.
Plane Reflection – Learning Outcomes
7.02 reflection in plane mirrors (1)
The Law of Reflection Smooth, shiny surfaces allow you to see an image. The angle of incidence=the angle of reflection Incident ray and reflective ray.
OBJECTIVES 1) Trace light rays as they reflect from a plane mirror.
Presentation transcript:

12.2 Reflection of light How do you look in others’ eyes? Laws of reflection Regular and diffuse reflection Check-point 1 How a plane mirror forms an image Check-point 2 ? 1 2 ? 3 12.2 Reflection of light

How do you look in others’ eyes? Make two plane mirrors stand perpendicular to each other and look at yourself at the joints of mirrors. This is the same as what other people see you! 12.2 Reflection of light

1 Laws of reflection A ray of light bounces off a plane mirror. mirror normal angle of incidence angle of reflection incident ray reflected ray mirror This is an example of reflection of light. 12.2 Reflection of light

Experiment 12a Laws of reflection Direct a ray of light at a plane mirror from different angles. full circle protractor ray-box mirror strip Any relations between angle of incidence i and angle of reflection r ? incident ray reflected ray 12.2 Reflection of light

Experiment 12a Video Simulation Laws of reflection 12.2 Reflection of light

1 Laws of reflection angle of incidence = angle of reflection normal incident ray reflected ray mirror Also see Simulation program 1.1 in Physics at Work Multimedia CD-ROM 1. 12.2 Reflection of light

all lie in the same plane. 1 Laws of reflection The incident ray, the reflected ray and the normal all lie in the same plane. normal incident ray reflected ray mirror 12.2 Reflection of light

1 Laws of reflection 12.2 Reflection of light

2 Regular and diffuse reflection Regular reflection on a flat, smooth surface e.g. mirror parallel incident rays parallel reflected rays 12.2 Reflection of light

2 Regular and diffuse reflection on a rough, not perfectly smooth surface e.g. cover of a book parallel incident rays reflected rays in different directions 12.2 Reflection of light

Check-point 1 1 The angle between the incident... 2 True or false: Reflection of… 3 The angle between an incident... 12.2 Reflection of light

Check-point 1 - Q1 The angle between the incident ray and the __________ is called the angle of incidence. normal The laws of reflection state that it is equal to the angle of __________. reflection 12.2 Reflection of light

Check-point 1 - Q2 True of false: Reflection of light by a rough surface does not obey the laws of reflection. (T / F) 12.2 Reflection of light

The angle between an incident ray and the mirror is 20. Check-point 1 - Q3 The angle between an incident ray and the mirror is 20. The angles of incidence and reflection are ____ and ____ respectively. 70 70 The mirror turns the ray by ____. 140 20 70 70 12.2 Reflection of light

Experiment 12b Direct a set of divergent rays at a plane mirror. Images formed by a plane mirror ray-box Direct a set of divergent rays at a plane mirror. Trace the reflected rays back to meet at a point. This is the image point of the ray-box lamp (object point) . How is the image point related to the object point? 12.2 Reflection of light

Experiment 12b Video Images formed by a plane mirror 12.2 Reflection of light

3 How a plane mirror forms an image Rays from object O become divergent after reflection. mirror 12.2 Reflection of light

3 How a plane mirror forms an image Reflected rays appear to come from I behind the mirror. I O I is a virtual image. mirror - cannot be picked up on a screen 12.2 Reflection of light

3 How a plane mirror forms an image Simulation 12.2 Reflection of light

3 How a plane mirror forms an image The image formed by a plane mirror is: 1 virtual 2 as far behind the mirror as the object is in front F F 3 of the same size as the object object image Also see Simulation program 1.3 in Physics at Work Multimedia CD-ROM 1. 4 laterally inverted mirror 12.2 Reflection of light

3 How a plane mirror forms an image Simulation 12.2 Reflection of light

3 How a plane mirror forms an image How to draw ray diagram of image formed by a plane mirror? Dotted rays are also virtual. The image is virtual and is represented by dotted lines. 12.2 Reflection of light

3 How a plane mirror forms an image 12.2 Reflection of light

Check-point 2 1 Which of the following... 2 Leon and Patrick look in a... 3 Letters P, Q are... 4 A boy of height 1.5 m stands... 12.2 Reflection of light

A Light rays come from the image to our eyes. Check-point 2 - Q1 Which of the following descriptions about the image formed by a plane mirror is incorrect? A Light rays come from the image to our eyes. B The image cannot be projected on a screen. C It is as far away from mirror as the object is in front. D It is virtual. 12.2 Reflection of light

Can they see themselves and each other in the mirror? Check-point 2 - Q2 Leon and Patrick look in a plane mirror placed directly in front of Leon. Can they see themselves and each other in the mirror? Leon can see himself but Patrick cannot. They can see each other. 12.2 Reflection of light

Letters P, Q are printed on a card as shown below. Check-point 2 - Q3 Letters P, Q are printed on a card as shown below. Sketch the image of the letters on the plane mirror. 12.2 Reflection of light

A boy of height 1.5 m stands 5 m in front of a plane mirror. Check-point 2 - Q4 A boy of height 1.5 m stands 5 m in front of a plane mirror. His image is ______ m tall and ______ m from him. 1.5 10 12.2 Reflection of light

The End 12.2 Reflection of light

Example 1 Turning directions of light If a ray of light is incident at one of the mirrors at 45°, complete the path of the ray. 45° 45° 45° 12.2 Reflection of light

Example 1 Turning directions of light How is the direction of the outgoing ray related to that of the incoming ray? The ray is turned back by the device. The outgoing and the incoming ray are parallel but opposite in direction. 12.2 Reflection of light

Return 12.2 Reflection of light

Example 2 A girl can just see her feet at the bottom edge of the Seeing the images A girl can just see her feet at the bottom edge of the mirror. 150 m Her eyes are 10 cm below the top of her head. 150 m (a) What is the distance between the girl and her image in the mirror? 12.2 Reflection of light

Example 2 Seeing the images (a) The image is as far behind the mirror as the object is in front.  Distance = 150  2 = 300 cm 12.2 Reflection of light

Example 2 Seeing the images (b) How high above the floor is the bottom edge of the mirror? 2 h 1 12.2 Reflection of light

The bottom edge of the mirror is 70 cm above the floor. Example 2 Seeing the images (b) How high above the floor is the bottom edge of the mirror? By laws of reflection, 1 = 2 h 1 2  h =  140 1 2 = 70 cm The bottom edge of the mirror is 70 cm above the floor. 12.2 Reflection of light

Example 2 Seeing the images (c) What is the minimum height of the top edge of the mirror if she is able to see the top of her head? 12.2 Reflection of light

Example 2 By laws of reflection, 3 = 4 a 4 1 10 cm  b = a =  10 2 Seeing the images By laws of reflection, 3 = 4 3 4 h 1 2 10 cm a b  b = a =  10 1 2 140 cm = 5 cm Minimum height of top edge of the mirror = b + 140 =145 cm above the floor 12.2 Reflection of light

Return 12.2 Reflection of light

Example 3 Checking back lights The driver in the car below wants to check whether the back lights on his car are both working. 12.2 Reflection of light

Example 3 (a) The image of P in the shop window is X. Checking back lights (a) The image of P in the shop window is X. (i) How far is X from the shop window? 1.3 m X 12.2 Reflection of light

Example 3 (a) The image of P in the shop window is X. Checking back lights (a) The image of P in the shop window is X. (ii) How far is X from rear-view mirror? 1.3 + 4.0 = 5.3 m X 12.2 Reflection of light

Example 3 (b) Where does the rear-view mirror form an image of P ? Checking back lights (b) Where does the rear-view mirror form an image of P ? 5.3 m behind the rear-view mirror. 1.3 m X 12.2 Reflection of light

Example 3 Checking back lights (c) Through reflections by the rear-view mirror and the shop window, the driver can see the number plate at the back of his car. Are the numbers laterally inverted? Since the number plate is laterally inverted twice, it looks normal in the rear-view mirror. 12.2 Reflection of light

Return 12.2 Reflection of light