normal: a line drawn perpendicular (90 ) from the point of incidence of the reflecting surface

Transcription

1 Ch 11 Reflecting Light off a Plane Mirror p. 313 Types of Mirrors (3) 1) Plane: flat fg 1 p. 313 law of reflection: the angle of incidence = the angle of reflection incident ray (in): the ray (light beam) of light that travels to the reflecting surface reflected ray: the ray of light that bounces off a reflecting surface normal: a line drawn perpendicular (90 ) from the point of incidence of the reflecting surface angle of incidence: the angle between the incident ray and the normal angle of reflection: the angle between the reflected ray and the normal Sec Reflecting Light off Surfaces p. 316 Specular (regular) reflection: light reflects off a smooth, shiny surface, flat ex: fg 1a p. 316 often produces an image (picture) ex: mirror, clear water, shinny metal E:\New school folder sept\new Science 8 probe\ch 11 mirrors and Lenses\notes\2011 Ch 11 notes.docx Last printed 5/22/ :21 AM Page 1 of 13

2 image appears behind the mirror, right-side up but backwards ex: fg 3 p. 317: Diffuse Reflection: light hits an irregular surface and is scattered in all directions no image produced still obeys the angle of incidence = angle of refection law fg 1b p. 316 do not see a reflection: ex: looking into green grass diffuse reflection easier on eyes: ex: lamp shades, stucco roofs, frosted bulbs HW: Read 11.3 cyu 11.2 E:\New school folder sept\new Science 8 probe\ch 11 mirrors and Lenses\notes\2011 Ch 11 notes.docx Last printed 5/22/ :21 AM Page 2 of 13

3 Ch 11 Reflecting Light off a Plane Mirror p. 313 of Mirrors (3) 1) Plane: fg 1 p. 313 law of : the angle of = the angle of incident ray (in): the (light beam) of light that travels the reflecting surface ray: the ray of light that off a reflecting surface : a line drawn perpendicular (90 ) from the point of incidence of the reflecting surface of incidence: the angle between the incident ray and the angle of : the angle between the ray and the normal Sec Light off Surfaces p. 316 (regular) reflection: light reflects off a, shiny surface, flat ex: fg 1a p. 316 often produces an (picture) ex: mirror, clear water, shinny metal E:\New school folder sept\new Science 8 probe\ch 11 mirrors and Lenses\notes\2011 Ch 11 notes.docx Last printed 5/22/ :21 AM Page 3 of 13

4 image appears the mirror, right-side up but ex: fg 3 p. 317: Reflection: light hits an surface and is in all directions image produced still obeys the angle of incidence = angle of refection fg 1b p. 316 do see a reflection: ex: looking into green grass diffuse reflection easier on eyes: ex: lamp, stucco roofs, frosted bulbs HW: Read 11.3 cyu 11.2 E:\New school folder sept\new Science 8 probe\ch 11 mirrors and Lenses\notes\2011 Ch 11 notes.docx Last printed 5/22/ :21 AM Page 4 of 13

5 Sec Describing Images p. 319 image: likeness of object (picture) fg 1 p. 319 ex: formed at back of eye formed on a screen optical device: produces an image ex: overhead machine Characteristics of Images: table 1 p ) Size: a) smaller then the object b) larger then the object c) same size as the object 2) Attitude: a) upright (right side up) b) inverted (upside down) 3) location of image (many possibilities) a) on the side of the lens opposite the object b) closer to the optical device then to the object c) behind mirror, in front of mirror, etc 4) Type: a) real image (can be placed on a screen) b) virtual image (can be seen only by looking at or though an optical device) ex: microscope Lab 11.5 Curved Mirrors p. 323 Types of mirrors (3) a) flat (plane) b) convex: reflecting surface is on the outside of the curved surface fg 1 p. 323 ex: back of a spoon c) concave: reflecting surface is on the inside of the curved surface fg 2 p. 323 ex: shaped like a cave, inside of the spoon Sec Using Curved Mirrors 2 kinds p ) concave mirror fg 1 p. 326 shaped like a cave principal focus: position where reflected parallel light rays come together focal length: the distance from the principal focus to the middle of the mirror principal axis: a line through the center of the mirror that includes the principal focus focuses parallel light rays to principal focus fg 1 p. 326 when object is beyond the principal focus real image in front of the mirror can appear on a screen E:\New school folder sept\new Science 8 probe\ch 11 mirrors and Lenses\notes\2011 Ch 11 notes.docx Last printed 5/22/ :21 AM Page 5 of 13

6 2) convex mirror fg 2 p. 326 shaped like a vex principal focus: position where parallel light rays appear to reflect from: rays diverge (spread apart) spreads light rays out virtual image behind the mirror can not be put on a screen USING CONCAVE MIRRORS fg 3 p. 326 concave mirror gathers light from distant place & focuses it on: your eye, telescope, camera film, digital camera fg 4 p. 327 concave cosmetic / make-up mirror object is placed inside the principal focus of a concave mirror virtual, upright, farther from the mirror then the object, enlarged image Using Convex Mirrors Curved surface reflects light from all parts of a room or area into your eye large field of view Ex: fg 5a p. 327 Ex: surveillance mirrors Ex: car side mirrors fg 6 p. 327 upright, smaller, farther away images E:\New school folder sept\new Science 8 probe\ch 11 mirrors and Lenses\notes\2011 Ch 11 notes.docx Last printed 5/22/ :21 AM Page 6 of 13

7 Sec Describing p. 319 image: of object (picture) fg 1 p. ex: formed at back of eye formed on a screen device: produces an ex: overhead machine of Images: table 1 p ) : a) smaller then the object b) larger then the object c) size as the object 2) : a) upright (right side up) b) (upside down) 3) of image (many possibilities) a) on the side of the lens the object b) closer to the optical device then to the object c) behind mirror, in front of mirror, etc 4) : a) image (can be placed on a ) b) image (can be seen only by looking at or though an optical ) ex: Lab 11.5 Curved Mirrors p. 323 Types of mirrors (3) a) flat ( ) b) : reflecting surface is on the outside of the curved surface fg 1 p. 323 ex: of a spoon c) : reflecting surface is on the inside of the curved surface fg 2 p. 323 ex: shaped like a, inside of the spoon Sec Using Mirrors 2 kinds p ) mirror fg 1 p. 326 shaped like a cave focus: position where reflected parallel light rays come focal : the from the principal focus to the middle of the mirror principal : a line through the center of the mirror that includes the principal focuses parallel light rays to principal fg 1 p. 326 when is beyond the principal focus image in front of the mirror can appear on a E:\New school folder sept\new Science 8 probe\ch 11 mirrors and Lenses\notes\2011 Ch 11 notes.docx Last printed 5/22/ :21 AM Page 7 of 13

8 2) mirror fg 2 p. 326 shaped like a vex principal : position where parallel light rays appear to from: rays (spread apart) light rays out image behind the mirror can be put on a screen USING CONCAVE MIRRORS fg 3 p. 326 concave mirror gathers light from place & focuses it on: your eye, telescope, camera film, digital camera fg 4 p. 327 concave mirror object is placed the principal focus of a concave mirror, upright, farther from the mirror then the object, image Using Convex Mirrors Curved surface light from all parts of a room or area into your eye large of view Ex: fg 5a p. 327 Ex: mirrors Ex: car mirrors fg 6 p. 327, smaller, away images E:\New school folder sept\new Science 8 probe\ch 11 mirrors and Lenses\notes\2011 Ch 11 notes.docx Last printed 5/22/ :21 AM Page 8 of 13

9 summary: Image Characteristics of Different Mirrors p. 328 Demonstrate with giant concave mirrors PLANE MIRROR CONCAVE MIRROR (object is closer to the mirror than the principal focus) fg 4 p. 327 CONCAVE MIRROR (object is farther from the mirror then the principal focus) fg 1 p. 326 SIZE Same size as object Larger than object Larger than the object but becomes smaller as object distance increases ATTITUDE Upright Upright Inverted Upright CONVEX MIRROR Smaller than object LOCATION Behind mirror Same distance from mirror as object Behind mirror Farther from the mirror than the object In front of mirror Distance varies depending on distance of object Behind mirror Farther from the mirror than the object TYPE OF IMAGE virtual Virtual real Virtual HW: cyu 11.6, 11.6 E:\New school folder sept\new Science 8 probe\ch 11 mirrors and Lenses\notes\2011 Ch 11 notes.docx Last printed 5/22/ :21 AM Page 9 of 13

10 Sec p. 329 The Refraction of Light Refraction: The bending of light as it passes from one medium (substance) to another medium ex: fg 1 light bends as it moves from one medium to another: water into air distorted image Sec Refracting Light in Lenses p. 331 Terms: fg 2 p. 329 incident ray: incomming light ray normal: imaginary line that is 90 (perpendicular) to the refracting surface refracted ray: the ray of light that has changed direction (bent) as it passed from 1 medium (material) to another (different materials have different densities) angle of incidence: angle between the incident ray and the normal angle of refraction: angle between the refracted ray and the normal lens: curved, transparent device that refracts (bends) light ex: fg 1 light reflects off pepper travels through lens refracts (magnifies) eyes other examples: eyeglasses, contact lenses, camera lenses Why? Speed of light differs in different materials (densities) change of speed produces a change of direction (refraction) fg 2 p. 331 E:\New school folder sept\new Science 8 probe\ch 11 mirrors and Lenses\notes\2011 Ch 11 notes.docx Last printed 5/22/ :21 AM Page 10 of 13

11 Designs of Lenses: (2 types) p ) convex: thick in middle, thin on outside fg 3 p. 332 principal focus: the position where parallel light rays come together focal length: distance from the principal focus to the center of the lens light rays converge (come together) 2) concave: fg4 p principal focus: the position where parallel rays appear to come from -light rays diverge (spread apart) Sec p. 329 The of Light E:\New school folder sept\new Science 8 probe\ch 11 mirrors and Lenses\notes\2011 Ch 11 notes.docx Last printed 5/22/ :21 AM Page 11 of 13

12 Refraction: The of light as it passes from one (substance) to another medium ex: fg 1 light as it moves from one medium to another: water into air image Terms: fg 2 p. 329 ray: incomming light ray normal: line that is 90 (perpendicular) to the surface ray: the ray of light that has changed direction ( ) as it passed from 1 medium (material) to another (different materials have different densities) of incidence: angle between the ray and normal the angle of : angle between the ray and the normal Sec Refracting Light in p. 331 lens:, transparent device that refracts (bends) light ex: fg 1 light reflects off pepper travels through lens refracts ( ) eyes other examples: eyeglasses, lenses, lenses Why? of light differs in materials (densities) of speed produces a change of direction ( ) fg 2 p E:\New school folder sept\new Science 8 probe\ch 11 mirrors and Lenses\notes\2011 Ch 11 notes.docx Last printed 5/22/ :21 AM Page 12 of 13

13 Designs of Lenses: (2 types) p ) : thick in middle, thin on outside fg 3 p. 332 principal : the position where light rays come focal : distance from the principal focus to the of the lens light rays (come together) 2) : fg4 p focus: the position where parallel rays to come from -light rays (spread apart) E:\New school folder sept\new Science 8 probe\ch 11 mirrors and Lenses\notes\2011 Ch 11 notes.docx Last printed 5/22/ :21 AM Page 13 of 13