8.3 Making a Periscope. Grade 8 Activity Plan

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Clare Cameron
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1 8.3 aking a eriscope rade 8 ctivity lan 1

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3 8.3 aking a eriscope bjectives: 1. o explain the concept of reflection. 2. o understand the formation and differences between real and virtual images. 3. o actively demonstrate reflection with the use of a periscope. eywords/concepts: luminous objects, illuminated objects, reflection and law of reflection, incident and reflected rays, angles of incidence and reflection, speed of light, normal line, concave and convex mirrors, periscope. ake-home product: periscope 3

4 egment frican roverb and ultural elevance (5 min.) etails he wind does not break a tree that bends. ukuma, anzania. re-test (10 min.) urn off all the lights in the room; get everyone to stand still and try to observe what is in the room. his demonstrates that darkness is the absence of light and light is very important for sight. ackground (10 min.) iscuss the importance of light to sight. iscuss flat versus curved mirrors and how it affects the image we see. se a spoon to demonstrate concave versus convex images. escribe reflection from bright and dark surfaces. ctivities (45 min.) llustrate the concept of reflection while making a periscope. ollow-up (10 min.) ost-test (15 min.) se the periscope to view different objects such as around corners above tables etc. ord search with a twist. pon finding the words in order, students should write a definition or words of association for the term. uggested interpretation of proverb: n life, one has to be accommodating to changes and able to adapt to different circumstances. f one is too rigid then life will be overwhelming and may lead to frustration. 4

5 ultural elevance r. ude gwemezie was born in igeria. e is the ounder & resident of - a railway consulting engineering and esearch ompany. e is an expert in structural mechanics, stress and failure analysis, design, testing and assessment of railway structures, and derailment investigations. e is also the ounder & resident of he ni ie o. nc. ni ie ompany nc. (ni) is a privately owned corporation that manufactures and supplies railway steel ties. e is the inventor of the he ni steel tie. his unique steel tie design won the old edal in the 1996 anadian esign ngineering wards. r. gwemezie is the ounder & resident of orfastnc - a company that manufactures functional, practical and cost effective rail-to-tie fastening systems. r. gwemezie is the inventor of the patented orfast ie late and lip ssembly products. ducation: h ngineering, cill niversity rincipal esearcher, ueens niversity djunct ssistant rofessor, ueens niversity 5

6 hree well-known light phenomena: reflection, refraction and scattering. et's take a second to discuss each one. eflection: a light ray strikes a smooth surface, such as a mirror, and bounces off. reflected ray always comes off the surface of a material at an angle equal to the angle at which the incoming ray hit the surface. n physics, you'll hear this called the law of reflection. cattering: when light strikes a rough surface, incoming light rays reflect at all sorts of angles because the surface is uneven. efraction: occurs when a ray of light passes from one transparent medium (air, let's say) to a second transparent medium (water). hen this happens, light changes speed and the light ray bends, either toward or away from what we call the normal line, an imaginary straight line that runs perpendicular to the surface of the object. he amount of bending, or angle of refraction, of the light wave depends on how much the material slows down the light. enses like those in a telescope or in a pair of glasses, take advantage of refraction. lens is a piece of glass or other transparent substance with curved sides for concentrating or dispersing light rays. enses serve to refract light at each boundary. s a ray of light enters the transparent material, it is refracted. s the same ray exits, it's refracted again. he net effect of the refraction at these two boundaries is that the light ray has changed directions. eriscope comes from two reek words, eri, meaning "around," and copus, "to look." periscope lets you look around walls, corners, or other obstacles. periscope includes two mirrors or reflecting prisms to change the direction of the light coming from the scene observed: the first deflects it down through a vertical tube; the second diverts it horizontally so that the scene can be viewed conveniently. 6

7 ctivity 1: poon demo urpose: o explain the concept of reflection by demonstrating how light behaves when it comes in contact with concave and convex surfaces. uggested format: mentor should illustrate and allow students to watch. tems uantity (for mentor) arge table spoon 1 lash light 1 rocedure: 1. urn off the lights in the room. llow students observe that darkness is the absence of light. 2. urn flashlight on and point it at something. llow students observe that sight is made possible when light is reflected off a subject. 3. se the spoon and flashlight to demonstrate how light behaves when it hits a curved reflective surface. 7

8 ctivity 2: aking a eriscope urpose: o actively demonstrate reflection with the use of a periscope. uggested format: students should have their individual set-ups, but should be encouraged to work in groups. tems uantity (for mentor and 10 students) lack ristol cards (60x32cm) 11 lat mirrors (10x7.5cm) 22 rotractors 11 asking tape 5rolls lashlight (with batteries) 1 rocedure: 1. race dimensions, as shown below, onto a piece of black ristol board 60 cm x 35 cm. 2. nsure that slits for mirrors are at 45 angles. se a protractor to help with these measurements. 3. ut out the outline of the periscope 4. old the panels to make the tube. old and tuck in the flaps, and join the edges with adhesive tape. 5. lide the mirrors through the angled slits so that they are parallel and facing each other. se adhesive tape provided to put the mirrors in place. 6. ook through the hole at the bottom of the box while holding it upright and see what happens. ilk containers can replace ristol board. ut off the top of the carton and proceed with cutting slits for the mirrors. f ristol board is to be used, mentor should cut them prior to session. lso, mentor should endeavour take a sample periscope along. 8

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10 ost-est ave students try to look at different things with the periscope and say whether or not they can see them. sk about how the periscope would work if the mirrors were at different angles. emonstrate with the periscope. ord earch with a twist. ind the word but in order to be credited, the student should say something about the word i.e. definition, function, importance. 10

11 11 eflection of ight ord earch

Chapter 5 Mirrors and Lenses

Chapter 5 Mirrors and Lenses Chapter 5 Notes: Mirrors and Lenses Name: Block: The Ray Model of Light The ray model of light represents light as a line, or ray, indicating the path of a beam of light. Light travels in straight lines