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$Math Alignment Project - Grand Erie District School First Class Web ...$

Solar OvensA solar oven, also called a solar cooker, is adevice that uses light from the Sun as its energysource. A solar oven transforms sunlight directlyinto heat that can be used for cooking or boilingwater (Figures 11.14 and 11.15). By making use ofsolar energy, precious resources can be saved. Forexample, trees are scarce in the Himalayas andusing solar energy instead of wood for heat helpspreserve forests.A solar oven uses several strategies forproducing heat, such as using a concave mirror toconcentrate the Sun’s rays, converting light toheat through absorption if the interior of the ovenis a dark colour, and using a clear cover so thatthe Sun’s rays can enter but very little heat canleave. The most efficient ovens create aninsulated space where the food is cooked.Figure 11.14 A man examines a solar oven that is heating water inLadakh, high in the Himalayan Mountains.Calculating MagnificationConcave mirrors have a number of usesincluding magnification. Magnification is themeasure of how much larger or smaller an imageis compared with the object itself. Themagnification of an image, as compared with theobject, may be the same size, enlarged, ordiminished (smaller). Magnification is expressedas a ratio of the height of the image to the heightof the object.Figure 11.15 This solar oven is located on a city rooftop.magnification =image heightobject heightorhM = ih oMagnification can also be determined by taking the ratio of thedistance from the image to the mirror and the distance from the objectto the mirror.Suggested Activity •D15 Inquiry Activity on page 430image distancedmagnification = or M = iobject distanced oThese are very general definitions of magnification. You can useeither formula to determine magnification. Be sure to use the sameunits for both heights or both distances in the calculation. However, nounits are required in the answer since the units cancel out during thecalculation. If the image is bigger than the object, then themagnification will be greater than 1. If the image is smaller than theobject, the magnification will be less than 1.Ray diagrams model the behaviour of light in mirrors and lenses.423
Practice Problems1. A microscope produces animage that is 1.00 × 10 –4 mhigh from an object that is4.00 × 10 –7 m high. What isthe magnification of themicroscope?2. A concave mirror producesan image on a wall that is30.0 cm high from an objectthat is 6.5 cm high. What isthe magnification of themirror?3. A pinhole camera producesa 2.34 × 10 –2 m image of abuilding that is actually50.0 m high. What is themagnification of the camera?Example Problem 11.1A microscope produces an image that is 5.50 × 10 –4 m high froman object that is 2.00 × 10 –6 m high. What is the magnification ofthis microscope?GivenObject height h o= 2.00 × 10 –6 mImage height h i= 5.50 × 10 –4 mRequiredMagnification M = ?Analysis and SolutionThe correct equation is M =Substitute the values and their units, and solve the problem.M =h ih o5.5 10 –4 mM =2.00 10 –6 m= 275h ih oParaphraseThe magnification of the microscope is 275 times.Practice Problems1. An object is placed 75 cmfrom a concave mirror. Areal image is produced50 cm away. What is themagnification?2. A person standing 3.00 mfrom a glass window seesher virtual image 3.00 m onthe other side. What is themagnification of thewindow?3. A camera creates a realimage of a tree 40 m away.The image is formed 3.0 cmbehind the lens. Find themagnification.Example Problem 11.2A candle is placed 22 cm from a concave mirror. A virtual image isproduced 53 cm from the mirror. What is the magnification?GivenObject distance d o= 22 cmImage distance d i= 53 cmRequiredMagnification M =?Analysis and SolutionThe correct equation is M =Substitute the values and their units, and solve the problem.M =d id o53 cmM =22 cm= 2.4d id oParaphraseThe magnification of the mirror is 2.4 times.424 UNIT D Light and Geometric Optics
Page 1 and 2: 11Ray diagrams model the behaviour
Page 3: 11.1MirrorsHere is a summary of wha
Page 6 and 7: Using the Law of ReflectionThe law
Page 8 and 9: Concave MirrorsA concave mirror, al
Page 12 and 13: Example Problem 11.3An electron mic
Page 14 and 15: Uses for Convex MirrorsIf you were
Page 16 and 17: D14 Skill Builder ActivityDrawing R
Page 18 and 19: D15 Inquiry Activity (continued)Fig
Page 20 and 21: 11.1 CHECK and REFLECTKey Concept R
Page 22 and 23: We use fibre optics systems to tran
Page 24 and 25: A ray of light is electromagnetic r
Page 26 and 27: How Light RefractsYou can picture t
Page 28 and 29: Snell’s LawThe phenomenon of refr
Page 30 and 31: At a certain angle, called the crit
Page 32 and 33: D19 Inquiry ActivityIndex of Refrac
Page 34 and 35: 11.2 CHECK and REFLECTKey Concept R
Page 36 and 37: Night vision goggles use lenses to
Page 38 and 39: Concave LensesA diverging lens is s
Page 40 and 41: Forming a Real ImageConvex lenses a
Page 42 and 43: Keep in mind the following points w
Page 44 and 45: Example Problem 11.11A camera with
Page 46 and 47: D24 Quick LabFocal LengthPurposeTo
Page 48 and 49: D26 Inquiry ActivityIdentifying the
Page 50 and 51: SCIENCEeverywhereSelf-AdjustingGlas
Page 52: 18. A student looks at the letters

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