2Introduction Objectives: Able to identify regular and diffuse reflectionAble to explain the laws of reflectionAble to construct the devices that use the concepts of reflection of lightTarget group: Secondary level (Grade-7)Duration/Mode: 2 periods (1hour 30 mins)/student-centred
3Reflection of Light Why can’t we see objects in the dark? Because there is no light.Light falls on the object.Light is sent back from the object and enters the eyes.We can see objects only when there is light.
4Content - Reflection of Light Formation of image in a plane mirror Section-A- Reflection of LightFormation of image ina plane mirrorSection-BSection-C- Periscope,KaleidoscopeQuitQuit
5Section-AReflection of lightWhen light is incident on the surface of an object some of the light is sent back and this phenomenon is called reflection of light.Click on each item to study more.ContentsTypesTermsLaws
6Section-A Reflection Regular Reflection Diffuse Reflection Click on each item to study more.
7Section-ARegular ReflectionWhen a parallel beam of light is incident on a plane mirror, the angles of incidence of all the rays are equal. Thus all the rays are reflected in one direction. Such reflection of light is called regular reflection.smooth surfaces
8Section-ADiffuse ReflectionWhen a parallel beam of light is incident on a rough surface, the rays are reflected in different directions. Such reflection of light is called diffuse reflection.rough surfaces
9N A O B i r Terms on reflection of light normal angle of incidence Section-ATerms on reflection of lightnormalangle of incidenceangle of reflectionNAOBirincident rayreflected rayMM'Click on each item to study more.
10Section-AAn incident rayAOA ray which represents the incident light is an incident ray.AOMM'
11N B A M' M O A reflected ray OB Section-AA reflected rayOBA ray which represents the reflected light is a reflected ray.AOMM'NB
12Section-AA normalONA line perpendicular to the surface at the point of incidence is called a normal.NAOMM'
13N A i M' M O An angle of incidence i Section-AAn angle of incidenceiAn angle between the incident ray and the normal is an angle of incidence.AOMM'Ni
14N B A r i M' M O An angle of reflection r Section-AAn angle of reflectionrAn angle between the reflected ray and the normal is an angle of reflection.NAOMM'iBr
152. The angle of incidence is equal to the angle of reflection. Section-ALaws of Reflection1. The incident ray, the reflected ray and the normal all lie in the same plane.2. The angle of incidence is equal tothe angle of reflection.Exercise-1
16Formation of image in a plane mirror Section-BFormation of image in a plane mirrorStand in front of a looking glass and look at your image.1. Can you receive your image on a screen ?2. Is the image erect or inverted?3. Is the image the same size or larger or smaller?4. What happens when you tilt your head to the right?5. How does the image move when you step forward or backward6. Where is the image formed ?
17Formation of image in a plane mirror Section-BFormation of image in a plane mirrorThe properties of the image formed in a plane mirrorare as follows:-The image is virtual.The image is erect.The image is of the same size as the object.The image is laterally inverted.The image is as far behind the mirror as the object is in front.The image is situated on the line passing through the object and perpendicular to the plane mirror.Exercise-2
18Section-CInstructions:Divide the class into six groups.Group A, B and C have to make a periscope.Group D, E and F have to make a kaleidoscope.Follow the instructions given in the websites.
19Section-CLet’s make a periscope.Click on the "Periscope" to view the web site.PeriscopeA periscope is an optical instrument that lets you see around corners and over walls.Click here to view the web page and make a periscope.
20let’s make a kaleidoscope. Section-CClick on the "Kaleidoscope" to view the web site.let’s make a kaleidoscope.KaleidoscopeA kaleidoscope is a tube containing mirrors and small pieces of coloured paper cut into tiny shapes.It uses reflections to make colourful patterns.Click here to view the web page and make a kaleidoscope.
21You are about to end this lesson. QuitYou are about to end this lesson.Are you sure?Click Yes to exit.Click No to return to the content slide.YesNo
22Science Group, B.E.H.S (2) Dagon, Union of Myanmar Web References– CreditCreated by –Daw Khin Khin Thein andScience Group, B.E.H.S (2) Dagon, Union of MyanmarWeb References–Quit