UNDERSTANDING TOTAL INTERNAL REFLECTION OF LIGHT.ppt

8/17/2019 UNDERSTANDING TOTAL INTERNAL REFLECTION OF LIGHT.ppt

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UNDERSTANDING

TOTAL INTERNALREFLECTION OF

LIGHT


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When light travels from a enser mei!m to

a less ense mei!m" it #ens a$a% from

normal& A small 'art of the in(ient ra% isrefle(te&

For light traveling thro!gh a ensermei!m to a less ense mei!m" the angle

of refra(tion"r in the less ense mei!m is

larger than the angle of in(ien(e"i in theenser mei!m&


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As the angle of in(ien(e in(reases" the

angle of refra(tion also in(reases& The

angle of refra(tion rea(hes )*o#efore theangle on in(ien(e oes& At the instan(e"

the refra(te ra% moves along the

#o!nar%&

This the limit" $hi(h the light ra% (an #e

refra(te in air as the angle of refra(tion inair (an+t #e greater than )*o&


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What is (riti(al angle,

The angle of in(ien(e in the

enser mei!m $hen the angle of

refra(tion in the less ensemei!m is e-!al to )*o&


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If the angle of in(ien(e is

in(rease f!rther" . i / ( 0" the light

no more refra(te" #!t internall%

refle(te&

Total internal refle(tion is $henthe ra% of light is entirel% refle(te

from the s!rfa(e at an angle of

in(ien(e&


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The t$o (onitions for total internal

refle(tion to o((!r are1

i& Light ra% 'asses from a enser

mei!m to a less ense mei!m&ii& The angle of in(ien(e in the

enser mei!m is greater than

the (riti(al angle of the mei!m&


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RELATIONSHI2

3ETWEEN CRITICAL

ANGLE AND

REFRACTI4E INDE5


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The refra(tive ine6 of a mei!m is

given as1

When light ra% is reverse" it follo$s

the same 'ath$a%& This is the

'rin(i'le of reversi#ilit% of light&

n 7 Sin i

Sin r


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The refra(tive ine6 $ater1

n 7 sin isin r

7 sin )*o

sin ( 7 8

sin (

( 7 sin98 . 8:n 0


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E5A;2LE 8

Whi(h light ra% e6hi#its totalinternal refle(tion,


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E5A;2LE <

The iagram sho$s a light ra% entering a

glass an refra(te& What is the refra(tive

ine6 of the glass #lo(=,


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E5A;2LE >

What is the (riti(al angle

of iamon $hi(h has arefra(tive ine6 of


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E5A;2LE @

a0 A glass #lo(= has a refra(tive

ine6 of 8&?


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E5A;2LE ?

Fig!re sho$s a light ra%s traveling

from air into a glass 'rism&

The (riti(al angle of the glass is&,


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TOTAL INTERNAL REFLECTION B

CRITICAL ANGLE

RELATIONSHI2 3ETWEEN

CRITICAL ANGLE AND

REFRACTI4E INDE5

CRITICAL ANGLE" C


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NATURAL 2HENO;ENA IN4OL4ING

TOTAL INTERNAL REFLECTION

80 ;irages

On hot a%" a 'erson traveling in a (ar $ill see an

imaginar% 'ool of $ater a''earing on the s!rfa(eof the roa&


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A22LICATIONS OF TOTAL

INTERNAL REFLECTION

80 2ERISCO2E B 3INOCULAR

O'ti(al instr!ments" ma=e !se of total internal

refle(tion $ithin glass 'rism rather than

refle(tion #% mirror& This !e to the fa(t that the(riti(al angle" ( of the glass .7@


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TOTAL INTERNAL REFLECTION B

CRITICAL ANGLE

NATURAL 2HENO;ENA

IN4OL4ING


A22LICATIONS OF


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UNDERSTANDING TOTAL INTERNAL REFLECTION OF LIGHT.ppt