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High School Part 1 /2 by SSL Technologies Physics Ex-48 Click PART-1 /2 Study the terminology of parabolic mirrors. Light rays.

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Presentation on theme: "High School Part 1 /2 by SSL Technologies Physics Ex-48 Click PART-1 /2 Study the terminology of parabolic mirrors. Light rays."— Presentation transcript:

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2 High School Part 1 /2 by SSL Technologies

3 Physics Ex-48 Click PART-1 /2 Study the terminology of parabolic mirrors. Light rays

4 Physics Ex-48 Click 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 Location of image (behind mirror or in front of mirror) Size Size (magnification) of image (larger or smaller than object) Attitude Attitude (whether the image is inverted or upright) Reversed Reversed (whether the image is reversed left-to-right, "mirror image")

5 Physics Ex-48 Click 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 label them as CASE-1 to CASE-6. Case-1: Object at infinity 6 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) Be sure to study each case!

6 Physics Ex-47 Click A ray parallel to the principal axis is reflected through the focal point (F). In order to draw images formed by curved mirrors, remember that : F C Principal axis Back of mirror V

7 Physics Ex-47 Click A ray that goes through the focal point (F) is reflected parallel to the principal axis. In order to draw images formed by curved mirrors, remember that : F C Principal axis Back of mirror V

8 Physics Ex-47 Click A ray that strikes the vertex (V) is reflected like a plane mirror. (Angle of incidence = Angle of reflection) In order to draw images formed by curved mirrors, remember that : F C Principal axis Back of mirror V Incident ray Reflected ray Incident ray Reflected ray

9 Physics Ex-47 Click A ray that goes through C (the center of curvature) is reflected back along its own path. In order to draw images formed by curved mirrors, remember that : F C Principal axis Back of mirror V

10 Physics Ex-48 Click This distance is known as the “focal length” (f). f REMEMBER The focal length (f) is from the focal point (F) to the vertex point (V).

11 Physics Ex-48 Click 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. Object at infinityNo image

12 Physics Ex-48 Click Object just beyond C Image is real, between C and F, inverted and reduced.

13 Physics Ex-48 Click Object at C Image is real, located at C, inverted and same height as object.

14 Physics Ex-48 Click Object between C and F Image is real, located beyond C, inverted and larger than the object.

15 Physics Ex-48 Click Object at F All rays are reflected parallel and thus no image is formed.

16 Physics Ex-48 Click Object between F and V (within the focal length) Image is virtual, located inside the mirror, upright and larger than the object.

17 Physics Ex-48 F Object Image An object is placed in front of a concave mirror. Find the location and characteristics of the image. TASK C C There are two steps in finding the image of a concave mirror. NOTE Draw a ray parallel to the principal axis and make it reflect through the focal point. Step-1 Draw a ray through the focal point and make it reflect parallel to the principal axis. Step-2 Object point Incident ray Reflected ray Incident ray Reflected ray Where the two reflected rays meet is the image point of the object point. Image point Characteristics of the image ~ Real (formed by reflected rays) ~ Inverted (upside down) ~ Smaller than the object Rather than draw an actual object, it is easier to draw the object as an arrow. This way, we can tell if the image is inverted or not. Such as right here! We can now draw the image. Since we are not given the location of the object, we can select any arbitrary location. Since the intersecting rays are both reflected rays, the image is real. Back of mirror 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. Click

18 Physics Ex-48 Click For convex mirrors, the image is always virtual, always located inside the mirror, always upright and always smaller than the object. N O T E Convex mirrors produce a very large field of view.

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20 Physics Ex-48 Question-1 State the rules for finding the image formed by a curved mirror. Click 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

21 Physics Ex-48 Question-2 State four characteristics of images. Click 1- Type (real or virtual) 2- Location (distance from mirror) 3- Magnification (size) 4- Attitude (upright or inverted Click

22 Physics Ex-48 Question-3 What is spherical aberration and how can it be eliminated? Click A fuzzy image produced by the fact that parallel rays do not pass through the focal point (F). It can be eliminated by making the mirror parabolic rather than spherical. Click

23 Physics Ex-48 Question-4 The diagram below displays a concave mirror and a beam of light striking the mirror. Label each part. Click Focal plane Principal axis Reflected ray Concave mirror Vertex (V) Focal point (F)

24 Physics Ex-48 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. Click Extended ray Incident ray Reflected ray

25 Physics Ex-48 Question-6 For each concave mirror below, draw the image. Click a) Image Image is real (formed by reflected rays)

26 Physics Ex-48 Question-6 Click b) For each concave mirror below, draw the image. Image Image is real (formed by reflected rays)

27 Physics Ex-48 Question-6 Click c) For each concave mirror below, draw the image. Image Image is real (formed by reflected rays)

28 Physics Ex-48 Question-6 Click d) For each concave mirror below, draw the image. Image Image is virtual (formed by extended rays)

29 Physics Ex-48 Question-7 The diagram below shows an illuminated object and its virtual image in a concave parabolic mirror. Determine the location of the focal point (F). Click C F REMINDER The focal point (F) is half the radius of curvature (C).

30 Physics Ex-48 Question-8 The diagram below shows an object in front of a convex parabolic mirror. Draw the image. Click Image is virtual, upright and smaller than the object. Image

31 Physics Ex-48 Question-9 Where must an object be placed in front of a concave mirror 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? ____________________________________ Click 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).

32 Physics Ex-48 Question-10 Consider a convex mirror, where must an object be placed so as produce a real image? Click Impossible, convex mirrors do not produce real images.

33 Physics Ex-48 Question-11 State the properties of a virtual image. Click A virtual image is formed by extended rays.

34 Physics Ex-48 Question-12 In what important way does a virtual image differ from a real image? Click In the fact that a virtual image cannot be projected onto a screen. Click

35 Physics Ex-48 Question-13 Consider an object placed in front of a concave mirror. Which one of the following statements correctly describes its image? Click 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. Image Back

36 Physics Ex-48 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. Incident ray Reflected ray Extended ray Incident ray Reflected ray Extended ray Image Click Image is virtual, upright and reduced.

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