PASCO OS-8515B User Manual Download

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Basic Optics System

OS-8515B

I n s t r u c t i o n M a n u a l w i th

E x p e r i m e n t G u i d e a n d

T e a c h e r s ’ N o te s

0 1 2 - 0 9 6 1 4B

Optics Bench

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OS-8

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Summary of Contents for OS-8515B

Page 1: ... Teachers Notes 012 09614B Optics Bench 9 0 9 0 80 70 60 50 60 70 80 20 30 40 10 0 10 40 30 20 70 60 50 80 90 80 50 60 70 20 30 40 10 0 10 40 30 20 50 C O M P O N E N T C O M P O N E N T N O R M A L N O R M A L B A S IC O P T IC S R A Y T A B L E O S 8 4 6 5 C T L N O R M A L ...

Page 2: ...rnal Reflection 15 Experiment 6 Convex and Concave Lenses 17 Experiment 7 Hollow Lens 19 Experiment 8 Lensmaker s Equation 21 Experiment 9 Apparent Depth 23 Experiment 10 Reversibility 27 Experiment 11 Dispersion 29 Experiment 12 Focal Length and Magnification of a Thin Lens 31 Experiment 13 Telescope 35 Experiment 14 Microscope 39 Experiment 15 Shadows 43 Telescope and Microscope Test Pattern 45 ...

Page 3: ...details O p t i c s B e n c h 90 90 80 70 60 50 60 70 80 20 30 40 10 0 10 40 30 20 70 60 50 80 90 80 50 60 70 20 30 40 10 0 10 40 30 20 50 C O M PO N EN T C O M PO N EN T N O R M AL N O R M AL BA SI C O PT IC S R AY TA BL E O S 84 65 C T L N O R M AL 1 2 3 4 5 6 7 8 a d e f c b Included Equipment Part Number 1 1 2 m Optics Bench OS 8508 2 Viewing Screen OS 8467 3 100 mm Mounted Lens 003 07204 4 20...

Page 4: ... Holder To use an unmounted lens on the bench place it in the adjustable lens holder It will hold any round lens between 20 and 75 mm in diameter Viewing Screen Mount the screen on the bench to view real images formed by lenses Ray Table and D shaped Lens Use the ray table and D shaped lens on a table top with the light source in ray box mode to study angles of incidence reflection and refraction ...

Page 5: ... measuring its radius of curvature 9 Apparent Depth page 23 Measure the apparent depth of the rhombus and determine its index of refraction by comparing the apparent depth to the actual thickness Ray Table Experiments These experiments use the Ray Table with the D shaped Lens and the Light Source in ray box mode 10 Reversibility page 27 Explore how the relationship between the angles of inci dence...

Page 6: ... Basic Optics System About the Experiments 6 ...

Page 7: ...e flat edge Place the flat edge on the paper so the lens stands stably without rocking 3 What is the resulting color where the three colors come together Record your observa tion in Table 1 1 4 Now block the green ray with a pencil What color results from adding red and blue light Record the result in Table 1 1 5 Block each color in succession to see the addition of the other two colors and com pl...

Page 8: ...ed light 3 For Trial 2 switch roles and repeat steps 1 and 2 with your partner observing lines that you have drawn Record the results in Table 1 2 For this trial you may try to trick your partner by drawing both lines the same color both red or both black for instance 4 Look at red and black lines under red light Which line is easier to see _________________________ Questions 1 What makes red ink ...

Page 9: ...olors as each fre quency is bent a different amount The rhombus is made of acrylic which has an index of refraction of 1 497 for light of wavelength 486 nm in a vacuum blue light 1 491 for wavelength 589 nm yellow and 1 489 for wavelength 651 nm red In general for visible light index of refrac tion increases with increasing frequency Procedure 1 Place the light source in ray box mode on a sheet of...

Page 10: ...gest angle c According to Snell s Law and the information given about the frequency dependence of the index of refraction for acrylic which color is predicted to refract at the largest angle 4 Without repositioning the light source turn the wheel to select the three primary color rays The colored rays should enter rhombus at the same angle that the white ray did Do the colored rays emerge from the...

Page 11: ...n the appropriate directions 4 Remove the light source and mirror from the paper On the paper draw the normal to the surface as in Figure 3 1 5 Measure the angle of incidence and the angle of reflection Measure these angles from the normal Record the angles in the first row Table 3 1 6 Repeat steps 1 5 with a different angle of incidence Repeat the procedure again to complete Table 3 1 with three ...

Page 12: ... and mirror from the paper 2 The place where the five reflected rays cross each other is the focal point of the mirror Mark the focal point 3 Measure the focal length from the center of the concave mirror sur face where the middle ray hit the mirror to the focal point Record the result in Table 3 2 4 Use a compass to draw a circle that matches the curvature of the mirror you will have to make seve...

Page 13: ...Figure 4 2 3 Mark the position of the parallel surfaces of the rhombus and trace the incident and transmitted rays Indicate the incoming and the outgoing rays with arrows in the appropriate direc tions Carefully mark where the rays enter and leave the rhombus 4 Remove the rhombus and draw a line on the paper connecting the points where the rays entered and left the rhombus This line represents the...

Page 14: ... of Table 4 1 use Snell s Law to calculate the index of refraction assuming the index of refraction of air is 1 0 2 Average the three values of the index of refraction Compare the average to the accepted value n 1 5 by calculating the percent difference Question What is the angle of the ray that leaves the rhombus relative to the ray that enters it Table 4 1 Data and Results Angle of Incidence Ang...

Page 15: ...the materials see Figure 5 1 In this experiment you will study a ray as it passes out of the rhombus from acrylic n 1 5 to air nair 1 If the incident angle θ1 is greater than the critical angle θc there is no refracted ray and total internal reflection occurs If θ1 θc the angle of the refracted ray θ2 is 90 as in Figure 5 2 In this case Snell s Law states n sin θc 1 sin 90 Solving for the sine of ...

Page 16: ...ide surface of the rhombus See Figure 5 4 Measure the angle between these rays using a protractor Extend these rays to make the protractor easier to use Note that this angle is twice the critical angle because the angle of incidence equals the angle of reflection Record the critical angle here θc _______ experimental 6 Calculate the critical angle using Snell s Law and the given index of refractio...

Page 17: ... one flat edge Place the flat edge on the paper so the lens stands stably without rocking 2 Trace around the surface of the lens and trace the incident and transmitted rays Indicate the incoming and the outgoing rays with arrows in the appropriate direc tions 3 The point where the outgoing rays cross is the focal point of the lens Measure the focal length from the center of the lens to the focal p...

Page 18: ...onverging diverging or parallel What does this tell you about the relationship between the focal lengths of these two lenses 6 Slide the convex and concave lenses apart by a few centimeters and observe the effect Then reverse the order of the lenses Trace at least one pattern of this type What is the effect of changing the distance between the lenses What is the effect of reversing their positions...

Page 19: ... see Figure 7 1 You will determine whether each section acts as a converging or diverging lens when it is a filled with water and surrounded by air and b filled with air and surrounded by water Procedure 1 Before you test the hollow lens make some predictions For every configuration in Table 7 1 predict whether incoming parallel rays will converge or diverge after passing through the lens Record y...

Page 20: ...the lens with water leaving section 1 filled with air Record your observation in Table 7 1 Repeat this step with air in different section of the lens to complete Table 7 1 Questions 1 Under what conditions is a plano convex lens converging Under what condi tions is it diverging 2 If a plano concave lens of an unknown material is a diverging lens when sur rounded by air is it possible to know wheth...

Page 21: ...ction n of the lens material eq 8 1 In this notation R is positive for a convex surface as viewed from outside the lens and R is negative for a concave surface as in Figure 8 1 Figure 8 1 Procedure 1 Place the light source in ray box mode on a white sheet of paper Turn the wheel to select three parallel rays Shine the rays straight into the convex lens see Fig ure 8 2 Note The lens has one flat ed...

Page 22: ...or having a radius of curvature equal to twice the focal length of the effective mirror see Figure 8 3 Trace the surface of the lens and mark the point where the central ray hits the surface Block the central ray and mark the point where the two outer rays cross Measure the distance from the lens surface to the point where the reflected rays cross The radius of curvature is twice this distance Rec...

Page 23: ... page flat on the table in front of you Hold a pencil horizontally a few centi meters above the paper With one eye closed or covered look down at the pencil and move your head side to side without moving the pencil Notice how the pencil appears to move relative to the words printed on the paper this phenomenon is known as parallax Now hold the tip of the pencil on the paper and check for parallax ...

Page 24: ... the pencil tip gently against the side of the rhombus and twist the pencil to make a light mark Erase the mark after you have finished this experiment Analysis 1 Measure the distance from the top of the rhombus to your pencil mark Record this apparent depth d in the first row of Table 9 1 2 Measure the thickness t of the rhombus and record it in Table 9 1 3 Use Equation 9 1 to calculate the index...

Page 25: ...he diverging rays back into the rhombus The point where these rays cross inside the rhombus is the appar ent position of the bottom of the rhombus when viewed through the top Analysis 1 Measure the apparent depth d and record it in Table 9 1 2 Use Equation 9 1 to calculate the index of refraction and record your result in Table 9 1 Questions 1 Of the two methods that you used to determine d which ...

Page 26: ... Basic Optics System Experiment 9 Apparent Depth 26 ...

Page 27: ... from the light source crosses the exact center of the ray table 3 Put the D shaped lens on the ray table exactly centered in the marked outline Required Equipment from Basic Optics System Ray Table D shaped Lens Light Source 9 0 9 0 8 0 7 0 60 50 60 70 80 20 30 40 1 0 0 10 40 30 2 0 7 0 60 50 8 0 9 0 8 0 50 60 7 0 2 0 30 40 1 0 0 1 0 40 30 2 0 50 C O M P O N E N T C O M P O N E N T N O R M A L N ...

Page 28: ...f incidence θi2 that you wrote in the third column of the table observe the corresponding angles of refraction θr2 and record them in the fourth column Analysis 1 Using your values for θi1 and θr1 and Snell s Law Equation 10 1 determine the index of refraction of acrylic nacrylic Assume the index of refraction of air nair is 1 0 eq 10 1 nacrylic ___________ from θi1 and θr1 2 Determine nacrylic ag...

Page 29: ...avelength dependence of a material s index of refraction is known as dispersion Setup 1 Place the light source in ray box mode on a flat tabletop Turn the wheel to select a single ray 2 Put the ray table in front of the light source so the ray from the light source crosses the exact center of the ray table see Figure 11 2 3 Put the acrylic D shaped lens on the ray table in the marked outline Turn ...

Page 30: ...at surface of the lens not at the curved surface As you continue to increase the angle of incidence watch the refracted light on the paper Analysis 1 At what angle of refraction do you begin to notice color separation in the refracted light 2 At what angle of refraction does the maximum color separation occur 3 What colors are present in the refracted ray Write them in the order of mini mum to max...

Page 31: ...ject size If the image is inverted M is negative Part I Object at Infinity In this part you will determine the focal length of the lens by making a single mea surement of di with Procedure 1 Hold the lens in one hand and the screen in the other hand Focus the image of a distant bright object such as a window or lamp across the room on the screen 2 Have your partner measure the distance from the le...

Page 32: ... screen or the light source move the lens to a second position where the image is in focus Measure the image distance and the object distance 5 Measure the object size and image size for this position also Note that you will not see the entire crossed arrow pattern Instead measure the image and object sizes as the distance between two index marks on the pattern see Figure 12 2 for example 6 Repeat...

Page 33: ...gnification 1 For the first two data points only the first two lines of Table 12 2 use image and object distances to calculate the magnification M at each position of the lens Record the results in Table 12 3 eq 12 2 Table 12 1 Image and Object Distances Distance from light source to screen do di 1 do 1 di Image Size Object Size 100 cm 90 cm 80 cm 70 cm 60 cm 50 cm Table 12 2 Focal Length f Result...

Page 34: ...nverted 2 Is the image real or virtual How do you know 3 Explain why for a given screen to object distance there are two lens positions where a clear image forms 4 By looking at the image how can you tell that the magnification is negative 5 You made three separate determinations of f by measuring it directly with a dis tant object from the x intercept of your graph and from the y intercept Where ...

Page 35: ...e distance between the object and the lens and di is the distance between the image and the lens The magnification M of a two lens system is equal to the product of the magnifica tions of the individual lenses eq 13 2 Set Up 1 Tape the paper grid pattern to the screen to serve as the object 2 The 200 mm lens is the objective lens the one closer to the object The 100 mm lens is the eyepiece lens th...

Page 36: ... the object shown as dotted lines in Figure 13 4 Move your head left and right or up and down by about a centimeter As you move your head the lines of the image may move relative to the lines of the object due to the parallax Adjust the eyepiece lens to eliminate parallax Do not move the objective lens When there is no parallax the lines in the center of the lens appear to be stuck to the object l...

Page 37: ...med by the objective lens Is it real or virtual Use a desk lamp to brightly illuminate the paper grid or replace the screen with the light source s crossed arrow object Hold a sheet of paper vertically where you think the image is Do you see the image Is it inverted or upright Remove the sheet of paper and hold a pencil in the same place Look through eyepiece lens you will see two images one of th...

Page 38: ... Basic Optics System Experiment 13 Telescope 38 ...

Page 39: ...the distance between the object and the lens and di is the distance between the image and the lens The magnification M of a two lens system is equal to the product of the magnifica tions of the individual lenses eq 14 2 Set Up 1 Tape the paper grid pattern to the screen to serve as the object 2 The 100 mm lens is the objective lens the one closer to the object The 200 mm lens is the eyepiece lens ...

Page 40: ...nd down by about a centimeter As you move your head the lines of the image may move relative to the lines of the object due to the parallax Adjust the eyepiece lens to eliminate parallax Do not move the objective lens When there is no parallax the lines in the center of the lens appear to be stuck to the object lines Note Even when there is no parallax the lines may appear to move near the edges o...

Page 41: ...by the Objective Lens Where is the image formed by the objective lens Is it real or virtual Us a desk lamp to brightly illuminate the paper grid or replace the screen with the light source s crossed arrow object Hold a sheet of paper vertically where you think the image is Do you see the image Is it inverted or upright Remove the sheet of paper and hold a pencil in the same place Look through eyep...

Page 42: ... Basic Optics System Experiment 14 Microscope 42 ...

Page 43: ...encil about 5 cm away from the screen so its shadow is cast on the screen Now turn the light source around so the crossed arrow illuminates the pencil and screen How does the shadow change 3 Rotate the light source back to the point source position Plug in the second light source Make a sketch of the shadow of the pencil Label the umbra and the pen umbra 4 Move the pencil away and toward the scree...

Page 44: ... Basic Optics System Experiment 15 Shadows 44 ...

Page 45: ... Model No OS 8515B Telescope and Microscope Test Pattern 45 Telescope and Microscope Test Pattern Attach a copy of this pattern to the viewing screen for experiments 13 and 14 1 cm grid ...

Page 46: ... Basic Optics System Telescope and Microscope Test Pattern 46 ...

Page 47: ...ause it reflects red light and absorbs other colors Under blue light red ink absorbs most of the visible light 2 Under red light red ink is difficult to see because both ink and paper reflect most of the visible light Experiment 2 Prism Notes on procedure Step 3 a Red Orange Yellow Green and Blue are seen in that order b Blue is refracted at the largest angle c Blue is predicted to refract at the ...

Page 48: ...ment 5 Total Internal Reflection Typical results Step 5 Measured critical angle θc 41 0 Step 6 Calculated critical angle θc sin 1 1 n sin 1 1 1 5 41 8 Step 7 Difference 1 9 Answers to questions 1 The internally reflected ray becomes much brighter when the incident angle is larger than the critical angle 2 The critical angle is greater for red light This tells us that the index of refraction is sma...

Page 49: ...ing or converging under water because its index of refraction may be less than or greater than that of water Experiment 8 Lensmaker s Equation Typical results Step 3 Measured focal length f 12 0 cm Step 4 Measured focal distance of reflected rays R 2 6 0 cm Radius of curvature R 12 0 cm Step 5 Calculated focal length Step 6 Difference 0 8 The actual radius of curvature or the lens is about 12 7 cm...

Page 50: ...ecision of less than 1 mm Using the ray tracing method the points at which the rays crossed had a larger uncertainty due to the thickness of the light beams 2 For the typical data above the percent differences between the accepted and experimental values of n are 0 7 for Part 1 and 5 for Part 2 Experiment 10 Reversibility Typical results Table 1 1 Results d t n Part 1 Parallax method 2 12 cm 3 18 ...

Page 51: ...iceable before then depending on the light in the room 2 Maximum separation occurs at about 85 beyond that the violet is totally internally reflected 3 In order the colors seen are red orange yellow green cyan blue violet though not all colors may be resolvable depending on the room light 4 With an incident angle of 40 the violet refracted at 76 and the red at 73 therefore nred 1 488 and nblue 1 5...

Page 52: ...cm 1 do cm 1 1 di cm 1 Image Size Object Size 100 cm 88 5 11 5 0 0113 0 0870 5 5 mm 42 mm 11 0 89 0 0 0909 0 0112 81 mm 10 mm 90 cm 78 3 11 7 0 0128 0 0855 11 3 78 7 0 0885 0 0127 80 cm 68 0 12 0 0 0147 0 0833 11 5 68 5 0 0870 0 0146 70 cm 57 7 12 3 0 0173 0 0813 11 9 58 1 0 0840 0 0172 60 cm 47 1 12 9 0 0212 0 0775 12 3 47 7 0 0813 0 0210 50 cm 36 0 14 0 0 0278 0 0714 13 4 36 6 0 0746 0 0273 Tabl...

Page 53: ...focal lengths Experiment 14 Microscope Typical results Answers to questions 1 The image is inverted 2 It is a virtual image Further study Image Formed by the Objective Lens The objective lens forms a real upright image to see it hold a sheet of paper at distance di1 from the objective When a pencil is placed at this location it s vir Table 13 1 Results Position of Objective Lens 63 4 cm Position o...

Page 54: ...ignificant The theoretical limit is 10 cm or the focal length of the objective lens Experiment 15 Shadows When the pencil is illuminated by the point source the shadow appears sharper than when illuminated by a dis tributed light source the crossed arrow object When illuminated by both point sources the pencil casts two shadows The area where the shadows overlap is the umbra The areas of partial s...

Page 55: ... are not sold for profit Reproduction under any other circumstances without the written con sent of PASCO scientific is prohibited Trademarks PASCO and PASCO scientific are trademarks or registered trademarks of PASCO scientific in the United States and or in other coun tries All other brands products or service names are or may be trademarks or service marks of and are used to identify products o...

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