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In simple terms ?

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In simple terms ?

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The refractive index is

The equation you give, referred to as Snell's Law (http://en.wikipedia.org/wiki/Snell's_law) tells you how much a beam of light will bend (refract) when it crosses between media with different indices of refraction.

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Simon Bridge

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imagine a lifeguard sees a swimmer in trouble - it is important that he gets to the swimmer in the shortest possible time.

He

If he runs across the sand at v and swims at a lesser speed u ... what is the best path for him to take?

Go work it out - at the end of which, you will understand Snell's law.

Light always takes the path of least time.

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I would write the relationship as

Speed in air/ speed in medium = sine of angle in air/ sine of angle in medium

This also means that it = wavelength in air/ wavelength in medium

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Thanks I understand now , but what about the sini/sinr law ?

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the sinei/siner law is just another way to state that light (any wave) changes speed as it passes from one medium into another.

The ratio speed in air(vacuum) / speed in medium is a constant known as the refractive index of the medium with respect to air. This is also the ratio sinei/siner

It is given the symbol n

In general speed in medium 1/ speed in medium 2 = sine angle in 1/sine angle in 2 and is known as the refractive index of medium 2 with respect to medium 1

This is Snell's law.

The ratio speed in air(vacuum) / speed in medium is a constant known as the refractive index of the medium with respect to air. This is also the ratio sinei/siner

It is given the symbol n

In general speed in medium 1/ speed in medium 2 = sine angle in 1/sine angle in 2 and is known as the refractive index of medium 2 with respect to medium 1

This is Snell's law.

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Er I think that you all think that I don't know snell's law. Actually I know and understand why it is like that , but I was referring more to the visualisation in

My question. As in , the relationship between the incident angle and the refracted angle is related to the refractive index of both mediums right ? So if the light ray travels from air to glass, the ray will be refracted towards the

Normal but how much it is refracted depends on the difference in refractive index in both mediums right ? So my question is how exactly are the angles related to the refractive index in terms of visuals? To put it

More simply, how do you derive snell's law ?

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Simon Bridge

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The reply I gave youNormal but how much it is refracted depends on the difference in refractive index in both mediums right ? So my question is how exactly are the angles related to the refractive index in terms of visuals? To put it

More simply, how do you derive snell's law ?

Did you try it?

Put the lifeguard at position (0,d) and the swimmer at (s,-c) - the lifeguard has to enter the water at a position x: 0<x<s ... find position x that minimizes the time to reach the swimmer. (Relate it to the normal angles to the shoreline to get Snell's Law.)

If the lifeguard has some high speed w under ideal conditions - say on a track - then we can define a "refractive index" for the sand and the water by n

Snell's law is not restricted to light. Give it a go.

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Simon Bridge

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[edited out the spambot, thanks Cthugha]

The optical refractive index of a single material is defined as the ratio of the speed of light in a vacuum with the speed of light in the material.

But refraction is a wave property - water-waves for example, moving from deep (fast) water to shallow (slow) water turn towards the normal ... which is why waves always come directly in towards the beach.

Refraction is not*just* a wave property. The lifeguard in the example above also has to change his path when he enters the water - turning towards the normal - to get to the swimmer soonest. It is possible to give the beach and the water an analogous index which will be a constant for a given lifeguard at a particular time in his career.

The optical refractive index of a single material is defined as the ratio of the speed of light in a vacuum with the speed of light in the material.

But refraction is a wave property - water-waves for example, moving from deep (fast) water to shallow (slow) water turn towards the normal ... which is why waves always come directly in towards the beach.

Refraction is not

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Cthugha

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Brady43Willia is a kind of spambot that screens forums and writes answers that represent the first answer found in google or some other database when the thread title is entered. At the bottom of every post a little advertisement link to some shop is attached. I reported that post.Hi Brady43Willia, welcome to PF

I have seen this kind of bot in several other forums and it is very creepy how "low profile" spambots have become nowadays.

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Simon Bridge

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The link even looked like it belonged...

Once the lifeguard problem is completed, it leaves only the thorny question of how the light

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Claude Bile

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- The phase at the media boundary is equal for both regions.

- The wavelength is different in each region.

It turns out when you combine these two effects, you get a bend in the direction of propagation of the waves. This is reasonably simple to graph for yourself.

Claude.

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