Seeing Things Through Stuff Index of Refraction Hiding Diamonds and Dispersion First Do L11 Index of...

Seeing Things Through Stuff Index of

Refraction Hiding Diamonds

and

Dispersion

First Do L11 Index of Refraction Activity

Seeing Things Through Stuff Answers follow.

1) The Angles of Refraction (∠R) in glycerol are given on the table.

Compared to water, what is the same about how light refracts into glycerol or glass?

All patterns for the angles of refraction (∠R) in glycerol or glass are the same as those in water.

They are as follows: When light travels from air into glycerol along the

normal, it does not bend; it travels straight through OR i = R = 0º.

When light travels from air into glycerol, it bends toward the normal, or the angle of refraction (∠R) is always less than the angle of incidence ∠i .

When light travels from air into glycerol, as the angle of incidence (∠i) gets smaller, the angle of refraction (∠R) gets smaller.

The incident and refracted rays are always on the opposite side of the normal.

2) Compared to water, what is different about how light refracts from air into glycerol or glass?

For the same angle of incidence,the angles of refraction (∠R) in glycerol are smaller than the angles of refraction (∠R) in water.

OR Light refracts more in glycerol than it does in water.

The amount that light bends when going into a different medium is called its Index of Refraction.

The Index of Refraction is a number that indicates how much light refracts when going into a different medium.

The larger the number, the more light refracts or bends.

3) Light refracts (more / the same / less) in glycerol than it does in water.

4) The amount that light bends when going into a different medium is called its Index of Refraction.

5) Large indexes of Refraction bend light (more / the same / less) than low indexes of Refraction.

6) Draw the refracted rays relative to water for semi-circular containers filled with….

a)Vegetable Oil b) Diamond

c) Air

Vegetable oil has a larger Index of Refraction than water, so light refracts or bends more than it would going into water.

a)Vegetable Oil b) Diamond

c) Air

Diamond has a larger Index of Refraction than vegetable oil, so light refracts even more than it would going into vegetable oil.

6) Draw the refracted rays relative to water for semi-circular containers filled with….

a)Vegetable Oil b) Diamond

c) Air

Air has the same Index of Refraction as the air the light is coming from, so light does not refract at all. It is not moving into a different medium.

6) Draw the refracted rays relative to water for semi-circular containers filled with….

This is a picture of a public toilet in Switzerland that is made entirely out of one-way glass. No one can see you in there, but when you are inside, it looks like you're sitting in a clear glass box. http://www.snopes.com/photos/arts/toilet.asp

See-Through-Loo

Outside View

Inside View

7) What does this have to do with refraction?

See-Through-Loo

Outside View

Inside View

Whenever light passes from one medium to another…… it partially refracts and partially reflects.

7) What does this have to do with refraction?

Whenever light passes from one medium to another, it partially refracts. and partially reflects.

See-Through-Loo

Outside View

Inside View

7) What does this have to do with refraction?

Whenever light passes from one medium to another, it partially refracts and partially reflects.

See-Through-Loo

Outside View

Inside View

Did you notice the reflected ray in the activity?

Partial reflection / refraction alsooccurs in windows.

Part of the light striking the window refracts through and part reflects back into the room.

If there is a difference between light brightness on either side of a window, the light from the bright side will refract more intensely through and reflect more intensely back into the room.

The person in the room will see a strong reflection of themselves compared to the image refracted from the other side.

If there is a difference between light brightness on either side of a window, the light from the bright side will refract more intensely through and reflect more intensely back into the room.

The person in the room will see a strong reflection of themselves compared to the image refracted from the other side.

If one side of a window is dark, the light from the bright side will refract intensely through and reflect intensely back into the room.

The person in the room will only see a reflection of themselves and nothing refracted from the other side. In this case, the girl sees the boy. The boy sees his reflection.

If one side of a window is dark, the light from the bright side will refract intensely through and reflect intensely back into the room.

The person in the room will only see a reflection of themselves and nothing refracted from the other side. In this case, the boy sees the girl. The girl sees her reflection.

If glass is partially coated with a metal like aluminum or silver, the partial reflection is strengthened so that the difference in light intensity is not as important.

This is the principle of a one-way mirror.

Check out the One-Way Mirror Shoe Box.

Inside, the “Loo” is dark so that there is little light to refract out. Note the weak reflection from inside.

Outside, the “Loo” is bright so there is lots of light to reflect back and refract inside.

See-Through-Loo

Outside View

Inside View

This woman is transparent because light can pass through her, but we can still easily see her. Why?

What conditions would have to be met in order for something to be truly invisible?.

H. G. Wells wrote a science fiction novella in 1897 called “The Invisible Man”.

See-Through-Sue

Since the air in the semi-circular container has the same Index of Refraction as the air it is coming from……

8) Recall the refracted ray for semi-circular container filled with air.

We could imagine the semi-circular container was not there.

We can imagine it as just an outline in air.

This is the same as saying that light travels in straight lines. Remember Rectilinear Propagation?

If light travels froma region with one index of refraction into another region with the same index of refraction,there is no refracted or reflected ray.

We see transparent objects because they both reflect and refract light.

The shiny areas of this woman are well done. That’s the reflected light.

However, the refracted light, the light that comes through from behind her, should be more distorted. The brick mortar lines are much too regular.

This image is virtual. It was generated by computer only.

It is not real.

Notice the shiny areas of reflected light near the edge of these spheres.

The refracted light comes through from behind. The distortion of the lines indicates these are photographs and not virtual images.

In order to be truly invisible, an object would have to betransparent and have the same index of refraction as the surrounding medium.

This would result in no reflected or refracted light.

You can see this with Ghost Crystals.

Ghost Crystals are made from a polyacrylamide polymer. They are called hydrophilic because they are “water(hydro) loving (philic) “ All this means is that they absorb a lot of water - several hundred times their volume of water.

After they have absorbed all the water possible, these crystals have the same index of refraction as water.

If they are placed in air, they can be seen because they have a different index of refraction and will reflect and refract light.

If they are placed in water, they become invisible because they have the same index of refraction and will not reflect or refract light.

Hiding DiamondsThis property is one way jewelers can check for artificial diamonds. If placed in a solution with the same index of refraction as real diamonds, real diamonds become invisible. Fakes can be seen.

If you want to hide the Real Diamonds, just place them in the solution and it just looks like a jar of liquid.

The index of refraction or the amount that light bends entering a particular substance also depends on the colour of light.

Different colours refract slightly different amounts. This causes the colours in white to separate when refracting and is called Dispersion.

The index of refraction of diamond (~2.4) is higher than that of glass (~1.5-1.6). Therefore, diamond bends light more causing a greater Dispersion or separation of colours than glass.

Glass (~1.5-1.6). Diamond (~2.4)