Presentation is loading. Please wait.

Presentation is loading. Please wait.

© Boardworks Ltd 2003 Reflection 3.2 (a) Reflection of light Core Describe the formation, and give the characteristics, of an optical image by a plane.

Similar presentations


Presentation on theme: "© Boardworks Ltd 2003 Reflection 3.2 (a) Reflection of light Core Describe the formation, and give the characteristics, of an optical image by a plane."— Presentation transcript:

1 © Boardworks Ltd 2003 Reflection 3.2 (a) Reflection of light Core Describe the formation, and give the characteristics, of an optical image by a plane mirror Use the law angle of incidence = angle of reflection Supplement Perform simple constructions, measurements and calculations

2 © Boardworks Ltd 2003 Objectives Recall that light travels in straight lines. Draw accurate ray diagrams. Describe how we see objects. Define the words opaque and transparent. Describe the images formed in a plane mirror. Recall how the angle of incidence and angle of reflection are related for a plane mirror. Describe the differences between convex and concave mirrors.

3 © Boardworks Ltd 2003 Light rays A light ray is a narrow beam of light. When drawing light diagrams always….. 1. Use a ruler. 2. Add an arrow to show the direction the light ray is travelling in.

4 © Boardworks Ltd 2003 How does light travel? 1)Fill a clear glass trough or empty fish tank with smoke. 2)Shine rays of light through the tank and describe what you see.

5 © Boardworks Ltd 2003 Light travels in straight lines Your experiment shows that light travels in straight lines. What every day consequences do you think this fact has? You can not see around corners. Shadows are formed in the area behind an object where light can not reach.

6 © Boardworks Ltd 2003 Seeing objects How do we see an object? Do we see all objects in the same way? There are two ways we see objects….. We see some objects because they are light sources. We see some objects by reflected light.

7 © Boardworks Ltd 2003 Seeing objects Light sourcesObjects seen by reflected light Sun Jupiter Firefly Moon Book Light bulb

8 © Boardworks Ltd 2003 Light sources How do light rays from the Sun and other light sources reach our eye? They travel in a straight line directly into our eye.

9 © Boardworks Ltd 2003 Reflected light How do light rays from a book and other such objects reach our eye? Light from the Sun or another light source strikes the book and some of the light is reflected into our eye.

10 © Boardworks Ltd 2003 Opaque and transparent materials Use a textbook or other source to find out what the words opaque and transparent mean. Opaque materials do not let light though. Transparent materials do let light through.

11 © Boardworks Ltd 2003 Reflections There are two types of m____. F__ mirrors and c____ mirrors. Flat mirrors are known as p___ mirrors. If a mirror curves in then it is a c_____ mirror, if it curves out it is a c____ mirror. irrorslat urved lane oncave onvex

12 © Boardworks Ltd 2003 Plane mirrors Write out the letters of the alphabet down one side of a piece of paper, then next to the letter draw what the letter would look like as seen in a mirror. What do you predict the letter ‘L’ would look like in a mirror? What do you predict the letter ‘P’ would look like in a mirror?

13 © Boardworks Ltd 2003 Right and left What happens to writing in a mirror? The writing in a mirror is laterally inverted or back to front. If you are wearing a T-shirt with some writing on and wave your right hand what will your image appear like in a mirror? The writing on your T-shirt will be back to front and your image will be waving it’s left hand.

14 © Boardworks Ltd 2003 Rear-view mirrors Imagine you are driving along in your car…… …and then you look up and see the following in your mirror….. …with your knowledge of mirrors how must the writing be written on the vehicle?

15 © Boardworks Ltd 2003 Reading in Mirrors In small groups, take it in turns to read the list of words on the next slide with your back to the screen using a mirror. You can only move on to the next word when you read the first word correctly.  Put your results in a table like this:

16 © Boardworks Ltd 2003 Words DogManBall BatBikeAnts ParkFinsPink LitterSandyShark

17 © Boardworks Ltd 2003 Results A)Who read the words in the quickest time? B)Plot a bar chart of you r results like: C)What was the average time taken in your group?

18 © Boardworks Ltd 2003 Image size and distance For a plane mirror how does the size of the image and the image distance from the mirror relate to the original object? Object Image Image size and object size are the same. The image distance is the same as the object distance from the mirror.

19 © Boardworks Ltd 2003 Investigating reflection Apparatus:  Power pack  Ray box  Slit  Concave mirror  Protractor  Ruler The ray box will get very hot, be careful when handling it.

20 © Boardworks Ltd 2003 Investigating reflection 1. Place the concave mirror on a piece of paper. 2. Draw a line along the front of the mirror. 3. Shine rays of light at varying angles to the normal and record the position of the incident and reflected rays 6. Measure the incident angles and the reflected angles for each ray. Record your results in a table. Incident angle  i Reflected angle  r Reflected ray Incident ray 4. Draw a tangent to the mirror where the ray hits. 5. Draw a normal to the mirror (at right angles to the previous line).

21 © Boardworks Ltd 2003 Results  i/°  r/° What do you notice? Is there a pattern? Angle of incidence = Angle of reflection

22 © Boardworks Ltd 2003 Using plane mirrors By positioning two plane mirrors at 45° to each other at either end of a tube we can make a _________. periscope Periscopes are used in __________. submarines

23 © Boardworks Ltd 2003 Reflection : Curved mirrors Concave reflectors are used to focus signals from distant satellites. Convex reflectors are used to widen the field of view.

24 © Boardworks Ltd 2003 Which of the following is not a light source? A.The Sun B.A star C.Traffic lights D.A book

25 © Boardworks Ltd 2003 Which of the following is not seen by reflected light? A.Your hand B.Jupiter C.Light bulb D.The Moon

26 © Boardworks Ltd 2003 Which of the following is the most opaque? A.Milk B.Sea water C.Air D.Drinking water

27 © Boardworks Ltd 2003 What do we call the area behind an object where light can not reach? A.Transparent B.Shadow C.Opaque D.Outline

28 © Boardworks Ltd 2003 Which statement below is untrue for the image in a plane mirror? A.It is laterally inverted B.It is real C.It is same size as the object D.It is the same distance from the mirror as the object

29 © Boardworks Ltd 2003 Objectives Recall that light travels in straight lines. Draw accurate ray diagrams. Describe how we see objects. Define the words opaque and transparent. Describe the images formed in a plane mirror. Recall how the angle of incidence and angle of reflection are related for a plane mirror.

30 © Boardworks Ltd 2003 = What I should know: The law of reflection: the angle = the angle of incidence of reflection A periscope uses 2 mirrors, set at 45° to the horizontal. The image in a plane mirror is: as far behind the mirror as the object is in front, the line joining the image to the object is at 90° to the mirror, a virtual image (no light rays go through it), the same size as the object, laterally inverted. What I should be able to do:  Carry out an experiment to test the law of reflection.  Draw a diagram of a periscope and explain how it works.  Describe an experiment to find out the position of an image in a plane mirror.  Understand a ray diagram which shows 2 light rays reflected off a mirror and into an eye.


Download ppt "© Boardworks Ltd 2003 Reflection 3.2 (a) Reflection of light Core Describe the formation, and give the characteristics, of an optical image by a plane."

Similar presentations


Ads by Google