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1 Reflaction Of Light

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1 Reflaction Of Light

1. 1. REFLECTION OF LIGHT
2. 2. Home Previous Next Help
3. 3. Home Previous Next Help
4. 4. Home Previous Next Help
5. 5. REFLECTION OF LIGHT Home Previous Next Help
6. 6. Light Travels in Straight Lines • A ray is the direction or path along which Home Previous light energy flows. In a diagram, rays are Next represented by lines with arrowheads. Help • A collection of rays is called a beam.
7. 7. THE LAWS OF REFLECTION Home FIRST LAWS Previous Next The incident ray, the reflected ray and Help the nornal all lie in the same plane SECOND LAWS The angle of incidence, I is equal to the angle of reflection, r
8. 8. THE LAWS OF REFLECTION Home When a ray of light strikes a plane mirror, the light ray reflects off the mirror. Reflection involves a change in Previous direction of the light ray. The convention used to express the Next direction of a light ray is to indicate the angle which the light ray makes Help with a normal drawn to the surface of the mirror. The angle of incidence is the angle between this normal and the incident ray; the angle of reflection is the angle between this normal and the reflected ray. According to the law of reflection, the angle of incidence equals the angle of reflection. These concepts are illustrated in the animation at the right.
9. 9. Image Formation for Plane Mirrors In the animation Home above, an object is positioned in front Previous of a plane mirror. The plane mirror Next will produce an image of the object Help on the opposite side of the mirror. The distance from the onject to the mirror equal the distance from the image to the mirror. Any person viewing this image must sight at this image position.
10. 10. Image Formation in Plane Mirrors 1. Draw the image of the Home Distance of the Distance of the object. object image 2. Pick one extreme on Previous the image of the object and draw the reflected ray which Next will travel to the eye as it sights at this Help point 3. Draw the incident ray object image for light traveling from the corresponding extreme on the object to the mirror. 4. Repeat steps 2 and 3 normal for all other Eye extremities on the object. Plane mirror
11. 11. Check Your Understanding Home • Explain why emergency vehicles such as ambulances are often marked on the front hood with reversed lettering Previous (e.g., ECNALUBMA). Answer: AMBULANCE Next Help • If Suzie stands 3 feet in front of a plane mirror, how far from the person will her image be located? Answer: 6 feet • If a toddler crawls towards a mirror at a rate of 0.25 m/s, then at what speed will the toddler and the toddler's image approach each other? Answer : 0.25 m/s
12. 12. The image of an object in a plane mirror Home (a) Same size as object Previous (b) Laterally inverted (c) virtual Next (d) As far behind the mirror Help
13. 13. Home Previous Next Help
14. 14. CONVEX MIRROR Home Previous Next Help
15. 15. If a concave mirror is thought of as being a slice of a sphere, then there would be a CURVED MIRROR line passing through the center of the sphere and attaching to the mirror in the exact center of the mirror. This line is Home known as the principal axis. The point in the center of sphere from which the mirror was sliced is known as the center Previous of curvature and is denoted by the letter C in the diagram below. The point on the mirror's surface where the Next principal axis meets the mirror is known as the vertex and is denoted by the letter A in the diagram below. The vertex Help is the geometric center of the mirror. Midway between the vertex and the center of curvature is a point known as the focal point; the focal point is denoted by the letter F in the diagram below. The distance from the vertex to the center of curvature is known as the radius of curvature (abbreviated by "R"). The radius of curvature is the radius of the sphere from which the mirror was cut. Finally, the distance from the mirror to the focal point is known as the focal length (abbreviated by "f"). Since the focal point is the midpoint of the line segment adjoining the vertex and the center of curvature, the focal length would be one-half the radius of curvature.
16. 16. Ray diagrams of convex and concave mirror Two rules of reflection for concave mirrors. They are: Home Any incident ray traveling parallel to the principal axis on the way to Previous a concave mirror will pass through the focal point upon reflection. Any incident ray passing through the focal point on the way to a Next concave mirror will travel parallel to the principal axis upon reflection. Help The revised rules can be stated as follows: Any incident ray traveling parallel to the principal axis on the way to a convex mirror will reflect in a manner that its extension will pass through the focal point. Any incident ray traveling towards a convex mirror such that its extension passes through the focal point will reflect and travel parallel to the principal axis.
17. 17. Concave mirror Convex mirror F C C F P principal axis Any incident ray traveling Any incident ray traveling parallel to the principal axis parallel to the principal axis on the way to a convex on the way to a concave mirror will reflect in a mirror will pass through the manner that its extension will focal point upon reflection. pass through the focal point.
18. 18. Concave mirror Convex mirror F C P C F Any incident ray passing Any incident ray traveling through the focal point on towards a convex mirror the way to a concave mirror such that its extension will travel parallel to the passes through the focal principal axis upon point will reflect and travel reflection. parallel to the principal axis.
19. 19. Concave mirror Convex mirror P F C C F A line through the centre of A line through the centre of curvature, C from the top curvature, C from the top of the object of the object
20. 20. Characteristics: • Virtual • Upright Applications : • magnified Shaving mirror 1. U < f I
21. 21. Characteristics: Applications : • Virtual Sport light • Upright • magnified 2. U = f
22. 22. Characteristics: • real Applications : • inverted • magnified Projector 3. f < U < 2f I
23. 23. Characteristics: • real Applications : • inverted Reflector in the projector • same size 4. U = 2f or at C I
24. 24. Characteristics: • real Applications : • inverted telescope • diminished 5. U > 2f or behind C I
25. 25. Characteristics: • virtual • inverted • diminished 6. Infinity object C F I P
26. 26. Characteristics: • virtual • upright • diminished 4. U > f F C O F I
27. 27. Characteristics: • virtual • Upright • diminished 4. U < f F C F O I
28. 28. APLICATION OF REFLECTION OF LIGHT Home Previous Next Help
29. 29. Rear view mirror Home Previous Next Help
30. 30. Home Dentist mirror Previous Next Help
31. 31. Periscope Home Previous Next Help
32. 32. Activity Home Previous •2 plane mirror •1 manila card Next •1 scissors Help •1 tape •1 candle
33. 33. Prosedure Home Previous Next Help