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8K Light (1).ppt

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Boardworks Ltd 20041 of 20 Boardworks Ltd 20061 of 47KS3 Physics8K Light Boardworks Ltd 20041 of 20 Boardworks Ltd 20062 of 478K LightContnts !hat is "ight# $f"ction $fraction S%&&ary acti'itis Co"o%r Boardworks Ltd 20041 of 20 Boardworks Ltd 20063 of 47Light carries energy and travels as a wave.Light travels at a speed of 300,000,000 metres per second, which is much faster than the speed of sound.Light waves travel in straight lines.!hat is "ight# Boardworks Ltd 20041 of 20 Boardworks Ltd 20064 of 471( Investigate how light travels using a glass trough filled with smoke. Use a slit to send rays of light into the tank and describe what you see.2( Investigate which materials let light through by holding different materials between a lamp and a screen. )n'stigating "ight Light waves travel in straight "ins( *rans+arnt material lets almost all the light pass through. *rans"%cnt material only allows some of the light through. ,+a-% material does not allow light to pass through. Boardworks Ltd 20041 of 20 Boardworks Ltd 2006. of 47!hich &atria"s "t "ight thro%gh# Boardworks Ltd 20041 of 20 Boardworks Ltd 20066 of 47An obect that gives out light is described as "%&ino%s.Light tra'"s in a straight "in dirct"y into th y(/ow do w s things#!ow does light from a luminous obect such as a light bulb reach the eye"An obect that does not give out light is non0"%&ino%s.Light fro& th "ight so%rc hits th 1ook and so& of this "ight!ow does your eye see a non0"%&ino%s obect such as a book"is rf"ctd into th y( Boardworks Ltd 20041 of 20 Boardworks Ltd 20067 of 478K LightContnts !hat is "ight# $f"ction $fraction S%&&ary acti'itis Co"o%r Boardworks Ltd 20041 of 20 Boardworks Ltd 20068 of 47#bects that do not rf"ct "ight w""$$f"cti' &atria"s#bects that rf"ct "ight w""$!ave smooth, shiny surfaces and are usually pale colours.%ive clear images because they reflect light regularly.!ave rough, matt surfaces and are usually dark colours.%ive diffuse images &ordo not give any images' because they reflect light irregularly. Boardworks Ltd 20041 of 20 Boardworks Ltd 20062 of 47(orking in pairs, one person is the )timer* and the other person is the )reader*.+he )reader* turns their back and has to read a list of words using a mirror. +hey must read each word correctly before moving on to the ne,t word. - . +he )timer* measures the time taken and the results for the whole class are recorded in a table like this$$ading in &irrors 3 instr%ctions1( (ho read the words in the /uickest time"2( 0lot a bar chart of the results.3( (hat was the average time taken in the class" Boardworks Ltd 20041 of 20 Boardworks Ltd 200610 of 47A plane mirror reflects light regularly so it produces a clear image, which is the same si1e as the obect.+he image appears the same distance behind the mirror as the obect is in front of it.(hen an obect is reflected in a plane mirror, left appears as right and right appears as left. +his type of reversal is called "atra" in'rsion.!hat is "atra" in'rsion#(hat is diffrnt about the image compared to the obect" Boardworks Ltd 20041 of 20 Boardworks Ltd 200611 of 471( 2i, a plane mirror to a piece of paper and draw around it.ang" iang" r2( 3raw a normal &at 405' through the centre of the mirror outline.3( Use a ray bo, to shine an incident ray at the mirror 6 plot the incident and reflected rays.4( 7easure the angles ofincidence -i. and reflection -r. and record the results..( 8epeat for another four angles

of incidence.6( (hat do the results show"$f"ction in'stigation Boardworks Ltd 20041 of 20 Boardworks Ltd 200612 of 47$f"ction ray diagra& Boardworks Ltd 20041 of 20 Boardworks Ltd 200613 of 47+he two plane mirrors must be positioned at 9:5 to each other. Light is reflected at right angles from the top mirror onto the bottom mirror and into the eye of the viewer.(here are periscopes used"4sing rf"ction8eflection can be very useful.!igh;visibility strips are very reflective and make sure thatthis cyclist gets noticed when there is little light.!ow does a periscope use reflection" Boardworks Ltd 20041 of 20 Boardworks Ltd 200614 of 47$f"ction s%&&ary Boardworks Ltd 20041 of 20 Boardworks Ltd 20061. of 47$f"ction 3 tr% or fa"s# Boardworks Ltd 20041 of 20 Boardworks Ltd 200616 of 478K LightContnts !hat is "ight# $f"ction $fraction S%&&ary acti'itis Co"o%r Boardworks Ltd 20041 of 20 Boardworks Ltd 200617 of 47$fraction at th air0g"ass 1o%ndary Boardworks Ltd 20041 of 20 Boardworks Ltd 200618 of 471( 0lace a rectangular glass block on a sheet of paper and draw around it.2( 3raw a normal at 405 to the top surface of the block.3( o colours are reflected and so it appears black.!ow do we see the different colours in this flower"+his part absorbs all colours e,cept red and green. It reflects red and green light, and so appears yellow.+his part absorbs no colours. It reflects all the colours and so appears white.+his skin absorbs all colours e,cept red and so is seen as red. Boardworks Ltd 20041 of 20 Boardworks Ltd 200638 of 47A rd fi"tr absorbs all colours?A 1"% fi"tr absorbs all colours?A grn fi"tr absorbs all colours...?apart from red light.?apart from blue light.?apart from green light.4sing fi"trs of +ri&ary co"o%rsA filter absorbs some colours of white light and lets other colours through to create coloured light. Boardworks Ltd 20041 of 20 Boardworks Ltd 200632 of 47A &agnta fi"tr absorbs all colours?A cyan fi"tr absorbs all colours?A y""ow fi"tr absorbs all colours...?apart from red and blue.?apart from green and blue.?apart from red and green.4sing fi"trs of scondary co"o%rs Boardworks Ltd 20041 of 20 Boardworks Ltd 200640 of 47Sing co"o%rs in co"o%rd "ight Boardworks Ltd 20041 of 20 Boardworks Ltd 200641 of 47/ow do w s co"o%rs in co"o%rd "ight# Boardworks Ltd 20041 of 20 Boardworks Ltd 200642 of 47Co"o%rd "ight acti'ity Boardworks Ltd 20041 of 20 Boardworks Ltd 200643 of 47!hat co"o%r dos it a++ar# Boardworks Ltd 20041 of 20 Boardworks Ltd 200644 of 478K LightContnts !hat is "ight# $f"ction $fraction S%&&ary acti'itis Co"o%r Boardworks Ltd 20041 of 20 Boardworks Ltd 20064. of 478"ossarya1sor+tion 3 (hen light is taken in by a material.dis+rsion 3 +he separating of the colours in light, e.g. when white light passes through a prism.i&ag 3 A copy of an obect formed when light is reflected from a mirror."ight 3 A form of energy that is detected by the eyes. "aw of rf"ction 3 (hen light is reflected, the angle of incidence e/uals the angle of reflection.+ris& 3 A block of glass, usually triangular, which separates the colours in light.rf"ction 3 +he bouncing back of light from a surface.rfraction 3 +he bending of light when it passes into a different medium, e.g. from air into glass.s+ctr%& 3 +he range of colours that make up white light. Boardworks Ltd 20041 of 20 Boardworks Ltd 200646 of 476nagra&s Boardworks Ltd 20041 of 20 Boardworks Ltd 200647 of 47

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