# The Naked Scientists Forum

#### smartscience

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##### Some questions about REFRACTION :)
« on: 03/11/2008 02:55:44 »
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« Last Edit: 14/12/2008 06:23:46 by smartscience »

#### RD

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##### Re: Some questions about REFRACTION :)
« Reply #1 on: 03/11/2008 03:26:55 »
Q1. The qualitative relationship between optical density and the direction of the incident and refracted rays.

A1. when a light ray travels from a less dense medium into a more dense medium its path is bent (refracted) towards the normal.
A ray moving from dense to less dense medium it is bent away from the normal.

("The normal" is a line perpendicular to the interface between the two media
where the ray makes the transition from one medium to the other).

There is the special case where a ray passing from a dense to less dense medium at an angle greater than the critical angle
will not be refracted but totally reflected.
« Last Edit: 03/11/2008 03:45:57 by RD »

#### smartscience

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##### Re: Some questions about REFRACTION :)
« Reply #2 on: 03/11/2008 03:43:12 »
thanks thanks thanks a lot` try other questions LOL

#### RD

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##### Re: Some questions about REFRACTION :)
« Reply #3 on: 03/11/2008 03:56:52 »
Q2. The qualitative relationship between the physical properties of density and optical density of a medium.

A2. Generally the denser the medium the greater its refractive index, (i.e. the greater its ability to refract), but there are exceptions

Q3. (i)The quantitive relationship between the speed of light in a vacuum, (ii) speed of light in a medium, (iii) index of refraction and the ratio of sine of the incident and refracted ray angles.

A3. (i) speed of light in a vacuum = c = 3×108 meters per second,

(ii) speed of light in medium = v = c/n  where n is the refractive index of the medium*.

(iii) Snells Law.

[* the refractive index is frequency dependent, this causes dispersion (e.g. rainbow)].
« Last Edit: 03/11/2008 04:13:26 by RD »

#### smartscience

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##### Re: Some questions about REFRACTION :)
« Reply #4 on: 03/11/2008 04:26:53 »
I remenber my teacher said that there is no relationship between physical properties of density and optical density of a medium,but how do i explain that they got no relationship?

#### RD

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##### Re: Some questions about REFRACTION :)
« Reply #5 on: 03/11/2008 05:16:11 »
how do i explain that they got no relationship?

Quote
The index of refraction is somewhat related to density, as one would expect.
This graph is for transparent minerals. Someone should make one for liquids and see what happens.
http://hypertextbook.com/physics/waves/refraction/

i.e. List a few examples of lower density substances which have higher refractive indexes than higher density substances.
e.g. vegetable oil is less dense than water, (it floats on water), but vegetable oil has a higher refractive index than water.
« Last Edit: 03/11/2008 05:24:31 by RD »

#### smartscience

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##### Re: Some questions about REFRACTION :)
« Reply #6 on: 03/11/2008 05:23:33 »
how do i explain that they got no relationship?

Quote
The index of refraction is somewhat related to density, as one would expect.
This graph is for transparent minerals. Someone should make one for liquids and see what happens.

i.e. List a few examples of lower density substances which have higher refractive indexes than higher density substances.

that seems making sense to me `thank you:)

#### gkef

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##### Re: Some questions about REFRACTION :)
« Reply #7 on: 03/11/2008 07:39:14 »
i think your teacher is mr.smith if i am correct, i need those answers too thanks :)

#### lightarrow

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##### Re: Some questions about REFRACTION :)
« Reply #8 on: 03/11/2008 08:17:26 »
RD, you shouldn't give complete answeres to someone who didn't even propose a solution to the questions.

#### lyner

• Guest
##### Re: Some questions about REFRACTION :)
« Reply #9 on: 03/11/2008 18:33:17 »
Let 'em do their own homework! Or sell them the answer. What are kids like these days?
BTW, density of air directly affects the refractive index - that's why you get mirages and twinkling stars.

#### The Naked Scientists Forum

##### Re: Some questions about REFRACTION :)
« Reply #9 on: 03/11/2008 18:33:17 »