Physics notes

Luminous Anobjectwhichis asourceoflight Lightcarriesenergyandtravels as awave
Lighttravelsat300000000mls or
Iid 300000km Is muchfasterthansound
Lightwavestravelsinstraightlines
Travelin astraightlinedirectlyintoour
eye
Opaque objects donotallowlight
NonLuminous Andejectwhichisnot asourceoflight to
throughthem transperant
passTranslucent
onesdo materialsonlylet

to
tb throughpartofthelight
Surfacesthatabsorb
lightmore are
malt surfaces andare usuallydark
colours
Lightfromthelamporanotherlightsource surfacesthatreflectlightwell are
strikesthebookandsomeofthelight is th shinysurfacesand areusually
reflectedinto our
eye TheygivedearimagesTheyreflect
pst.gg
thelightregularly
Glassreflects asmallamountof
light absorbs Therougherthesurfacethelight is
someoftherestandallowsmostofit topassthrough scattered in all directionsTheygiveno
ordiffusedimagesbecausetheyreflect
thelightirregularly
LateralinversionWhenan object is reflected in aplanemirrorleftappearsasrightandright
appearsas leftThistypeofreversaliscalledlateralinversion
Theimage isthesamedistancebehindthemirroristhesamedistancebehindthemirror
astheobject isinfront
Mirrors are goodreflectors butnotperfect theygive2reflections
Weuseglassprismsinstead ofmirrors in goodqualitybinoculars
andotherinstruments
Periscope anapparatusconsistingof atubeattachedto asetofmirrorsorprisms whichanobserver
by
typicallyin a submergedsubmarineorbehindahighobstacle canseethingsthatareotherwiseoutof
sight

Manynumbe


j n

ÉIIIIIIIIIIKÉÉIÉII
ofshadows
mmmm
oflight
sources
i
f
If lightfrom a lightsource is blocked
Thetwoplanemirrorsmustbepositionedat 45 it creates a shadowYoucanmake a
fromtheverticalLightisreflectedatrightangles shadow movingtheobjectclosertothe
fromthe
topmirrorontothebottommirrorand
by
lightsource Further fromthe smaller
away light
intotheeyeoftheviewer theshadowOpaqueNolightpassesthrough
transperantlightpassesthroughtranslucentlittle
lightpassesthroughLongestshadowsEarly
morninglate
afternoonNoonshortestornoshadow

, Refraction Bending
light
Thespeedoflightwavesdepends onthematerialthey aretravellingthrough
Whenlightenters a moredensemedium it slows down the of incidence angle
angle
Refracted
raybendstowardsthenormalPartofthelightrays slowsdown ofrefraction
AirEFastesterestlassistoweruses pthianghnygowesdirection


When theangle ofincidence is 00the lightray is not deviated
adence 0 If thelightenters anewmediumalongthenormal kioothenit
frog Undeviated
itgpgthfmggeo.tn doesnotbendbecause allofthelight slowsdownatthesametime
ray
Ifangleofincidence is O angleof refractionis00
Ifangleofincidence is O angleof reflection is00
Y angleofincidence is same as angleofreflection
angleofincidenceis biggerthanangleofrefractionCoisan
exception

White
lightAllIsformedwhen othercolours mixtogether
Spectrum colours ofwhitelight in sameorder
Thewhitelight
ray is splitinto a spectrum ofcoloursrainbowcolours Thisisknown
as Dispersion
Remember Richard Of YorkGaveBattleIn Vain
When lightenters a prism itbends itis refracted It alsobendswhenleavingthe
prismSomethingelsealsohappenswhitelightsplitsinto a spectrumofcolours
Thecolours are Differentcoloursoflight different
RedOrangeYellowGreenBlueIndigo Violet wavelengthsrefracted
wavelengthsDifferent

Inadeggopfdark
bluepurplecolour atdifferentamountsRefractedthe
shortestwavelength
thestéaitlet
lightis reflectedthemostRedlightis reflected
DViolet
2 WaterCrain
drops
Beerargéydactegomeotelitisidertoidiotetwhichis reflectedthemost
Primarycolours RedGreen Blue
SecondarycoloursMagentaCyan Yellow


t
doesared
why lookredinwhitelight
object




Ared absorbs red
only lightisreflected

ftp.g
object
thecoloursof
all the from theobject
into
youreye
my gang g g
Lb except
spectrum red sotheobject red
appears

g g g anyway g g
so
i
8588
Ipatinga prom
Fettig netted
sothe
oureye
appearsblack
thecoloursof
all the theobject
from into eye
your
object ta