Holt Chapter 14 Student Outline Light and Refraction Variables introduced or used in chapter: Quantity Symbol Units Speed of light frequency wavelength angle Object Distance Image Distance Radius of Curvature Focus Formula Chart Mirror Equation Magnification Relationship between R and f Sign Convention for Magnification Orientation Sign of M Type of Image Upright Inverted Ray P 1 F 2 C 3 Rules for Mirror Ray Diagrams Line drawn from Object to Mirror Line drawn from mirror to image after reflection Electromagnetic Spectrum Classification Wavelength Range Frequency Range Application Radio Microwaves Infrared Waves Visible Light Ultraviolet Light X-Rays Gamma Rays 1
Vocabulary: Define using complete sentences: 1. Electromagnetic Wave 2. Wave front 3. Wavelet 4. Ray 5. Reflection 6. Angle of Incidence 7. Angle of Reflection 8. Virtual Image 9. Concave Spherical Mirror 10. Real Image 11. Convex Spherical Mirror 12. Spherical aberration 13. Complementary colors 14. Linear polarization 15. Transmission Axis 2
Holt Chapter 15 Student Outline Refraction Variables introduced or used in chapter: Quantity Symbol Units Angle of Incidence Angle of Refraction Critical Angle Index of Refraction Object Distance Image Distance Focus Object Height Image Height P F C Ray Parallel Focal Central Index of Refraction Snell s Law Thin-Lens Equation Magnification Critical Angle Line drawn from Object to lens Formula Chart Rules for Lens Ray Diagrams Converging Lens Line drawn from lens to image Line drawn from Object to lens Diverging Lens Line drawn from lens to image 3
Vocabulary: Define using complete sentences: 1. Refraction 2. Index of Refraction 3. Snell s Law 4. Lens 5. Converging Lens 6. Diverging Lens 7. Magnification 8. Total Internal Reflection 9. Critical Angle 10. Fiber Optics 11. Mirage 12. Dispersion 13. Chromatic Aberration Questions: Answer using complete sentences: 14. When does refraction occur? 15. What is the difference between hyperopia and myopia? 4
Light and Optics Mirrors: 1. A concave spherical mirror has a focal length of 10.0 cm. Locate the image of a pencil that is placed upright 30.0 cm from the mirror. Find the magnification of the image. Is the image real/virtual, inverted/upright, reduced/enlarged? [15 cm, -0.5] 2. Find the image distance and magnification of a pencil that is placed upright 10.0 cm from the concave spherical mirror in question #1. Is the image real or virtual? Is the image inverted or upright? Is the image real/virtual, inverted/upright, reduced/enlarged? [no image] 3. Find the image distance and magnification of a pencil that is placed upright 5.0 cm from the concave spherical mirror in question #1. Is the image real or virtual? Is the image inverted or upright? Is the image real/virtual, inverted/upright, reduced/enlarged? [-10 cm, 2.0] 4. A concave shaving mirror has a focal length of 33 cm. Calculate the image position of a cologne bottle placed in front of the mirror at a distance of 93 cm. Calculate the magnification of the image. Is the image real/virtual, inverted/upright, reduced/enlarged? [-0.55] 5. A concave makeup mirror is designed so that a person 25.0 cm in front of it sees an upright image at a distance of 50.0 cm behind the mirror. What is the radius of curvature of the mirror? What is the magnification of the image? Is the image real/virtual, inverted/upright, reduced/enlarged? [R = 100 cm, 2.00] 6. A pen placed 11.0 cm from a concave spherical mirror produces a real image 13.2 cm from the mirror. What is the focal length of the mirror? What is the magnification of the image? If the pen is placed 27.0 cm from the mirror, what is the new position of the image? What is the magnification of the new image? Is the image real/virtual, inverted/upright, reduced/enlarged? [6 cm, -1.2, 7.71 cm, -0.286] 7. An upright pencil is placed in front of a convex mirror with a focal length of 8.00 cm. An upright image 2.50 cm tall is formed 4.44 cm behind the mirror. Find the position if the object, the magnification of the image and the height of the pencil. Is the image real/virtual, inverted/upright, reduced/enlarged? [9.978 cm, 0.445, 5.63 cm] 8. The image of a crayon appears to be 23.0 cm behind the surface of a convex mirror and is 1.70 cm tall. If the mirror s focal length is 46.0 cm, how far in front of the mirror is the crayon positioned? What is the magnification of the image? Is the image real/virtual, inverted/upright, reduced/enlarged? How tall is the actual crayon? [46 cm, 0.50, 3.4 cm] 9. A convex mirror with a focal length of 0.25 m forms a 0.080 m tall image of an automobile at a distance of 0.24 m behind the mirror. What is the magnification of the image? Where is the car located and how tall is it? Is the image real/virtual, inverted/upright, reduced/enlarged? [6m, 0.04, 2 m] 10. A convex mirror with focal length 33 cm forms an image of a soda bottle at a distance of 19 cm behind the mirror. If the height of the image is 7.0 cm, where is the object located and how tall is it? What is the magnification of the image? Is the image real/virtual, inverted/upright, reduced/enlarged? [44.79 cm, 16.50 cm, 0.424] 5
Lenses: **Make sure your calculator is in DEGREES!!!** 11. A light ray of wavelength 589 nm (produced by a sodium lamp) traveling through air strikes a smooth, flat slab of crown glass at an angle of 30.0 o to the normal. Index of refraction of crown glass is 1.52. Find the angle of refraction, Θ r. [19.2 degrees] 12. Find the angle of refraction for a ray of light that enters a bucket of water from air at an angle of 25.0 o to the normal. (n water = 1.333) [18.5 degrees] 13. A ray of light of vacuum wavelength 550 nm traveling in air enters a slab of transparent material. The incoming ray makes an angle of 40 o with the normal and the refracted ray make an angle of 26.0 o with the normal. Find the index of refraction of the transparent material. [1.47] 14. For each of the following cases will that light rays be bent toward or away from the normal? a. n i > n r, where Θ i = 20 o b. n i < n r, where Θ i = 20 o c. from air to glass with an angle of incidence of 30 o d. from glass to air with an angle of incidence of 30 o 15. An object is placed 30 cm in front of a converging lens and then 12.5 cm in front of a diverging lens. Both lenses have a focal length of 10.0 cm. For both cases, find the image distance and the magnification. Is the image real/virtual, inverted/upright, reduced/enlarged? [15 cm, -0.5; -5.56 cm, +0.445] 16. An object is placed 20 cm in front of a converging lens of focal length 10.0 cm. Find the image distance and magnification. Is the image real/virtual, inverted/upright, reduced/enlarged? [20 cm, -1, R, I] 17. An object placed 20 cm in front of a diverging lens of focal length 10 cm. Find the image distance and the magnification. Is the image real/virtual, inverted/upright, reduced/enlarged? [-6.67 cm, 0.33, V, U] 18. Fill in the missing values for the table: f p q M Converging Lens 6.0 cm -3.0 cm 2.9 cm 7.0 cm Diverging Lens -6.0 cm 4.0 cm 5.0 cm 0.50 Ray Diagram Practice: square on principal axis = F, little dot on principal axis = C 6
19 Converging Lens 20 21 7
22 23 24 8
25 26 9
27 28 10
29 30 11
31 32 12
Measuring the Index of Refraction Lab Materials: Ray box, Plastic rectangle prism, plastic triangle prism, ruler, protractor I. Plastic Rectangle 1. Place the rectangle in the space below and trace around it. 2. Using the ray box with one slit, trace the rays that appear outside of the rectangle. (R 1 & R 3 on diagram below). Make sure to draw arrows showing the direction the light is traveling. 3. Use a ruler to connect R 1 & R 3 to form R 2 within the rectangle. 4. With your ruler, carefully draw a dotted line normal to the object s surface where the light ray enters the object. Draw another one where the light ray leaves the object. Remember normal is perpendicular to the boundary. 5. Using a protractor, measure the angles of incidence and refraction where the light enters and where the light leaves the object. Remember to measure relative to normal. 6. Use Snell s Law to calculate the index of refraction of your material. You will make this calculation for each set of angles. Show work for both calculations. 7. Average the two values together. This is the material s index of refraction. Make sure it s larger than the smallest index of refraction 8. Use the definition of the index of refraction to calculate the speed of light through the material. (n = c/v) 9. Show all calculations below and make sure to label your diagram completely, including rays with R 1, R 2, R 3, angles of incidence (θ i) and angles of refraction (θ r) and show arrows for direction of light travel. R 1 θ i θ r R 2 θ i R 3 θ r Show ALL work! Light enters rectangle: Angle of incidence: Angle of refraction: Light leaves rectangle: Angle of incidence: Angle of refraction: 13
Index of refraction: Speed of light: II. Plastic Triangle 10. Place the triangle in the space below and trace around it. 11. Using the ray box with one slit, trace the rays that appear outside of the triangle. (R 1 & R 3 on diagram below). Make sure to draw arrows showing the direction the light is traveling. 12. Use a ruler to connect R 1 & R 3 to form R 2 within the triangle. 13. With your ruler, carefully draw a dotted line normal to the object s surface where the light ray enters the object. Draw another one where the light ray leaves the object. 14. Using a protractor, measure the angles of incidence and refraction where the light enters and where the light leaves the object. 15. Use Snell s Law to calculate the index of refraction of your material. You will make this calculation for each set of angles. Show work for both calculations. 16. Average the two values together. This is the material s index of refraction. Make sure it s larger than the smallest index of refraction 17. Use the definition of the index of refraction to calculate the speed of light through the material. (n = c/v) 18. Show all calculations below and make sure to label your diagram completely, including rays with R 1, R 2, R 3, angles of incidence (θ i) and angles of refraction (θ r) and show arrows for direction of light travel. R 1 θ i θ r R 2 θ i θ r R 3 Show ALL work! Light enters rectangle: Angle of incidence: Angle of refraction: Light leaves rectangle: Angle of incidence: Angle of refraction: Index of refraction: Speed of light: 14
Ray Tracing Lab Purpose: To investigate the law of reflection and how it applies to mirrors. To investigate the law of refraction and how it applies to lenses. To draw ray diagrams of real world mirrors and lenses. Materials: Ray Box Ruler Protractor Concave/Convex mirror Converging lens Diverging lens Procedure: Students have to do their own drawings. This is not really a group activity, but more of an equipment sharing experience. All drawings must be done with a straight edge or they will not be accepted! All angles must be labeled and all rays must be rays (arrows pointing in the direction of wave movement). The actual drawings for this lab will be done on the observation section of the packet. Concave Mirror 1. Place the concave mirror onto the paper. Trace the curve of the mirror onto the paper. 2. Using the plastic cover, block the light so that three beams of light are coming from the ray box. Shine them straight onto the mirror. 3. For each ray a. Trace the incident ray and the reflected ray. b. Draw in the normal. Then, using a protractor, measure the area of incidence and the angle of reflection. Label each angle with the appropriate measurement. 4. Label the focal point. What are the focal length and radius of curvature? Convex Mirror 1. Place the convex mirror onto the paper. Trace the curve of the mirror onto the paper. 2. Using the plastic cover, block the light so that three beams of light are coming from the ray box. Shine them straight onto the mirror. 3. For each ray a. Trace the incident ray, the reflected ray, and the virtual ray behind the mirror (dotted line). b. Draw in the normal. Then, using a protractor, measure the area of incidence and the angle of reflection. Label each angle with the appropriate measurement. 4. Label the focal point. What are the focal length and the radius of curvature? Converging Lens 1. Place the converging lens onto the paper. Trace the curves of the lens onto the paper. 2. Using the plastic cover, block the light so that 3 beams are coming from the ray box. 3. Shine the rays onto the lens. Trace the incident rays and the refracted rays. 4. Label the focal point. What is the focal length? Diverging Lens 1. Place the diverging lens onto the paper. Trace the curves of the lens onto the paper. 2. Using the plastic cover, block the light so that 3 beams are coming from the ray box. 3. Shine the rays onto the lens. Trace the incident rays and the refracted rays. 4. Include the virtual rays in front of the lens in your drawing. 5. Label the focal point. What is the focal length? Write Up for Ray Tracing 15
Summarize the Purpose of the Lab: Observations: Concave Mirror: Focal length = Convex Mirror: Focal length = Radius of curvature = Radius of curvature = Converging Lens: Focal Length = Diverging Lens: Focal Length = Analysis: 1. Use your observations of the mirrors to justify the law of reflection. Include some data to support your answer. 2. Light rays from the sun approach the surface of the Earth nearly parallel to each other (like the ray box). Why can you use a magnifying glass (a converging lens) to burn leaves with the light of the sun? Use physics and what you know about lenses in your answer. 3. For a concave mirror, does the radius of curvature have any effect on how neat the focal point is? Why or why not? 4. For a convex lens, does the radius of curvature have any effect on how neat the focal point is? Why or why not? 16
Extra Problems Light & Optics Terms to know: (don t have to write them out) Electromagnetic wave Focal length Electromagnetic spectrum Magnification Diffuse reflection Refraction Specular reflection Angle of refraction and how it changes as move Law of reflection from fast slow and slow fast Flat mirror Index of refraction Concave mirror Converging lens Convex mirror Diverging lens Real image Polarization Virtual image Color 1. What is the frequency of an electromagnetic wave with a wavelength of 1.0x 10 5 m, if the wave is traveling at 3 x 10 8 m/s? [3000 Hz] 2. If you are reading a book and you move 3 times as far away from the light source, how does the brightness at the new distance compare with that at the old distance? [1/9 as bright] 3. A 6.0 cm pencil is placed upright 10 cm from a flat mirror. How are s o and s i related? How are h o and h i related? Is the image real or virtual? Is the image upright or inverted? 4. A concave spherical mirror has a focal length of 15.0 cm. Locate the image of a pencil is placed upright 43 cm from the mirror. Find the magnification of the image. Is the image real or virtual? Is the image upright or inverted? Reduced or enlarged? [23.04 cm, -0.536, R,I,R] 5. A concave mirror is designed so that a person 35.0 cm in front of it sees an upright image at a distance of 70 cm behind the mirror. What is the focal length of the mirror? What is the radius of curvature? Is the image real or virtual? [70 cm, 140 cm, V] 6. A convex mirror with focal length of 45 cm forms a 0.80 cm tall image of a pencil at a distance of 20 cm behind the mirror. What is the magnification of the image? Where is the pencil located? How tall is the pencil? Is the image real or virtual? Is the image upright or inverted? [36 cm, 0.556, 1.489 cm, V,U] 7. A convex mirror with focal length of 43 cm forms an image of a bottle at a distance of 22 cm behind the mirror. If the height of the image is 8.5 cm, where is the object located and how tall is it? What is the magnification of the image? Is the image real or virtual? Is the image inverted or upright? [45.05 cm, 0.488, 17.42 cm, V,U] 8. A light ray traveling through air strikes a smooth pond of water (n water = 1.333) at an angle of 35 o to the normal. Find the angle of refraction. Sketch a picture of the situation. [25.49 o ] 9. A ray of light traveling in water (n water = 1.33), enters a slab of transparent material. The incoming ray makes an angle of 52 o with the normal and the refracted ray makes an angle of 61.2 o with the normal. Find the index of refraction of the transparent material. [1.199] 17
10. An object is placed 40 cm in front of a converging lens with a focal length of 12 cm. Find the image distance and magnification. Is the image real or virtual? Upright or inverted? Enlarged or reduced? [17.143 cm, -0.429, R, I, R] 11. An object is placed 15 cm in front of a diverging lens with a focal length of 12 cm. Fins the image distance and magnification. Is the image real or virtual? Upright or inverted? Enlarged or reduced? [-6.67 cm, 0.444, V,U,R] 12. An object is placed 5 cm from a converging lens with a focal length of 5 cm. Where is the image located? Is the image real or virtual? Upright or inverted? Enlarged or reduced? [no image] 13. An object is placed 10 cm from a converging lens with a focal length of 5 cm. Where is the image located? What is the magnification? Is the image real or virtual? Upright or inverted? Enlarged or reduced? [10 cm, -1, R, I, same] 18
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