velox
Retired
Why does the refractive index of a material equal the gradient of the line when u graph sin i against sin r ??
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prelim stuff (1 Viewer)
- Thread starter velox
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George W. Bush
Banned
it doesn't
unless you're talking about the special case where the inital medium is air which is close enough to a refractive index of one
there's a geometric proof based on hyugen's principle, try searching for it on the net (or derive yourself, once you know the result it's not that hard..just consider that the wavelet that gets to the new medium first will travel furthur..)
unless you're talking about the special case where the inital medium is air which is close enough to a refractive index of one
there's a geometric proof based on hyugen's principle, try searching for it on the net (or derive yourself, once you know the result it's not that hard..just consider that the wavelet that gets to the new medium first will travel furthur..)
velox
Retired
hmm, the sheet i did said that...its to do with snells law..Also the teacher said it did. And yes the initial medium was air 
so i look for hyugens principle?
so i look for hyugens principle?velox
Retired
??
velox
Retired
hmm, im lost here
George W. Bush
Banned
huygen's principle is that any point on the wave can be considered the source of a wavelet
or something like that
now when you have a wave come in at an angle to the second medium, the part of the wave that touches the medium first will travel slower so the wave will bend around, until all of the wave is in the medium. try drawing a diagran or just search on google for 'snell's law huygen's principle' or something.
or something like that
now when you have a wave come in at an angle to the second medium, the part of the wave that touches the medium first will travel slower so the wave will bend around, until all of the wave is in the medium. try drawing a diagran or just search on google for 'snell's law huygen's principle' or something.
JamiL
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snells law is n=sin i/sin r = Vi/Vr
where n= referective index
where n= referective index
George W. Bush
Banned
asdf
that is ONLY true if coming from air
and you're not really helping explain WHY
that is ONLY true if coming from air
and you're not really helping explain WHY
na/nb = sin @a / sin @b is applicable to all monochormatic rays, regardless of whether the initial medium is air/vaccuum...
the refractive index n = c/v.... which means how slow the em wave propagate with repective to its velocity in vacuum... hence, the greater the n, the slower the em wave will travel....
hence, na/nb is teh ratio of velocity of waves enterin from one medium to a second medium with respect to the velocity of light invaccuum... that ratio is not affected by which medium u started with initially, and which one u ended up with...
the refractive index n = c/v.... which means how slow the em wave propagate with repective to its velocity in vacuum... hence, the greater the n, the slower the em wave will travel....
hence, na/nb is teh ratio of velocity of waves enterin from one medium to a second medium with respect to the velocity of light invaccuum... that ratio is not affected by which medium u started with initially, and which one u ended up with...
George W. Bush
Banned
yes, jamil was rolling into the thread stating n = sini/sinr
velox
Retired
so back to the question why? or did i miss something....
be careful when you are saying refractive index... the index is standardised against the speed of light in vacuum... so when you r talking abt 2 mediums not from air to something, u need to use nf/ni = sin i / sin f
with air to somethign else, ni = 1...
with air to somethign else, ni = 1...