InClass

1. High School PHYSICS InClass by SSL Technologies with S. Lancione Exercise-48 Curved mirrors Part 1 /2

2. Curved mirrors PART-1 /2 Study the terminologyof parabolic mirrors. Light rays Click

3. Curved mirrors RULES FOR DRAWING RAYS IN CURVED MIRRORS A ray that is parallel to the principal axis is reflected through the principal focus (F). A ray passing through the principal focus (F) is reflected parallel to the principal axis. A ray passing through the center of curvature (C) is reflected back along its own path. Note that images have properties called "characteristics". Image characteristics include: Location of image (behind mirror or in front of mirror) Size (magnification) of image (larger or smaller than object) Attitude(whether the image is inverted or upright) Reversed(whether the image is reversed left-to-right, "mirror image") Click

4. 6 Concave mirrors  CONCAVE MIRRORS The characteristics of an image formed by a concave mirror depend on the location of the object. As it turns out, there are six “strategic” locations where an object may be placed. For each location, the image will be formed at a different place and with different characteristics. We will study the six different locations and labelthem as CASE-1 to CASE-6. Be sure to studyeach case! Case-1: Object at infinity Case-2: Object just beyond C Case-3: Object at C (center of curvature) Case-4: Object between C and F Case-5: Object at F (focal point) Case-6: Object between F and V (within focal length) Click

5. Principal axis C F Back of mirror In order to draw images formed by curved mirrors, remember that: A ray parallel to the principal axis is reflected through the focal point (F). MEMORIZE THIS! V Click

6. Principal axis C F Back of mirror In order to draw images formed by curved mirrors, remember that: A ray that goes through the focal point (F) is reflected parallel to the principal axis. MEMORIZE THIS! V Click

7. Principal axis C F Back of mirror In order to draw images formed by curved mirrors, remember that: A ray that strikes the vertex (V) is reflected like a plane mirror. (Angle of incidence = Angle of reflection) MEMORIZE THIS! Incident ray Incident ray V Reflected ray Reflected ray Click

8. Principal axis C F Back of mirror In order to draw images formed by curved mirrors, remember that: A ray that goes through C (the center of curvature) is reflected back along its own path. MEMORIZE THIS! V Click

9. Concave mirrors Important This distance is known as the “focal length” (f). f REMEMBER The focal length (f) isfrom the focal point (F)to the vertex point (V). Click

10. Concave mirrors Object at infinity No image Due to the great distance the object is from the mirror, all rays arrive at the mirror parallel to the principal axis. As a result, all rays focus at the focal point and no image is formed. Click

11. Concave mirrors Object just beyond C Image is real,between C and F,inverted and reduced. Click

12. Concave mirrors Object at C Image is real, located at C, inverted and same height as object. Click

13. Concave mirrors Object between C and F Image is real, located beyond C, inverted and larger than the object. Click

14. Concave mirrors Object at F All rays are reflectedparallel and thusno image is formed. Click

15. Concave mirrors Object between F and V(within the focal length) Image is virtual, located inside the mirror,upright and larger than the object. Click

16. TASK An object is placed in frontof a concave mirror. Find the location and characteristics of the image. Where the two reflected rays meet is the image point of the object point. Since we are not given the location of the object, we can select any arbitrary location. Step-2 Step-1 Draw a ray through the focal point and make it reflect parallel to the principal axis. Draw a ray parallel to the principal axisand make it reflect through the focal point. Such asright here! Like this Like this Object point Rather than draw an actual object, it is easier to draw the object as an arrow.This way, we can tell if theimage is inverted or not. Incident ray Incident ray Object C Objects consist of an infinite number of points. And each point has an infinite number of rays radiating outwards. Images also consist of an infinite number of points. Each point on the object has a corresponding point on the image. In locating an image, we take one point on the object and find its corresponding point (location) on the image object. As shown above, we usually take the (extreme) top point and find its corresponding point on the image object. C F Image We can now draw the image. Image point Reflected ray Back of mirror Reflected ray Characteristics of the image ~ Real (formed by reflected rays) ~ Inverted (upside down) ~ Smaller than the object NOTE There are two steps in finding the image of a concave mirror. Since the intersecting rays are both reflected rays, the image is real. Click Click Click Click Click Click Click Click Click Click Click Click Click

17. Convex mirrors Convex mirrors producea very large field of view. NOTE For convex mirrors, the image is always virtual, always located inside the mirror,always upright and always smaller than the object. Click

18. EXERCISES

19. Question-1 State the rules for finding the image formed by a curved mirror. 1- A ray parallel to the principal axis is reflected through the focal point (F). 2- A ray through the focal point (F) is reflected parallel to the principal axis. 3- A ray through the center of curvature (C) is reflected back along its own path. Click Click

20. Question-2 State four characteristics of images. 1- Type (real or virtual) 2- Location (distance from mirror) 3- Magnification (size) 4- Attitude (upright or inverted Click Click

21. Question-3 What is sphericalaberrationand how can it be eliminated? A fuzzy image produced by the fact that parallel rays do not passthrough the focal point (F). It can be eliminated by making the mirror parabolic rather thanspherical. Click Click

22. Question-4 The diagram below displays a concavemirror and a beam of light striking the mirror. Label each part. Focal plane Concave mirror Principal axis Vertex (V) Reflected ray Focal point (F) Click Click

23. Question-5 The diagram below illustrates the image of an object produced by a concave mirror. Label the incident ray, the reflected ray and the extended ray. Extended ray Incident ray Reflected ray Click Click

24. Question-6 For each concavemirror below, draw the image. a) Image Image is real (formed by reflected rays) Click Click

25. Question-6 For each concavemirror below, draw the image. b) Image Image is real (formed by reflected rays) Click Click

26. Question-6 For each concavemirror below, draw the image. c) Image Image is real (formed by reflected rays) Click Click

27. Question-6 For each concavemirror below, draw the image. d) Image Image is virtual (formed by extended rays) Click Click

28. Question-7 The diagram below shows an illuminated object and its virtualimage in a concave parabolic mirror. Determine the location of the focal point(F). F C REMINDER The focal point (F) is halfthe radius of curvature (C). Click Click Click

29. Question-8 The diagram below shows an object in front of a convexparabolicmirror. Draw the image. Image is virtual,upright and smallerthan the object. Image Click

30. Question-9 Where must an object be placed in front of a concavemirror so as to form an image that is: a) Smaller than object? ____________________________________ b) Inverted? ____________________________________ c) Virtual? ____________________________________ d) Inverted and magnified ? ____________________________________ e) Same height as object? ____________________________________ Just beyond the center of curvature (C). Beyond the focal point (F). Within the focal length (f). Between C and F. At the center of curvature (C). Click

31. Question-10 Consider a convexmirror, where must an object be placedso as produce a realimage? Impossible, convex mirrors do not produce real images. Click

32. Question-11 State the properties of a virtual image. A virtual image is formed by extended rays. Click

33. Question-12 In what important way does a virtual image differ from a real image? In the fact that a virtual image cannot be projected onto a screen. Click Click Click

34. Question-13 Consider an object placed in front of a concave mirror. Which oneof the following statements correctly describes its image? Back Image A) It is in front of the mirror, inverted, real and smaller than the object. B) It is behind the mirror, upright, virtual, and smaller than the object. C) It is in front of the mirror, upright, real and smaller than the object. D) It is behind the mirror, upright, virtual and larger than the object. Click

35. Question-18 An object is placed in front of a convex mirror as illustrated below. Draw and label the light rays necessary to locate the image. Reflected ray Incident ray Extended ray Incident ray Image Extended ray Reflected ray Image is virtual, upright and reduced. Click

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