Refraction in our Life

Total internal reflectionWhile looking from inside water, it is impossible to see the skies at the angles of more than 48.8o .

How does total internal reflection workYou can see from air this way (at this angle)

You cannot see from air at this angle any more

Still can see what’s in the air…

Watch Optical Fiber Demonstration

You can make one!

Dispertion

Light rays of different colours refract at slightly different angles.Dispersion is the refraction of white light into separate wavelengths, or colours.

Rainbow

The spoon may look broken in a glass of water.

The pattern of the light rays gets distorted due to refraction.

Broken Spoon Effect

the light rays bend twice: when they enter water and when they leave it

Broken Spoon Effect

Our eye see the the emerged part of the spoon shifted against the above the water part.

Apparent DepthObjects under water are not where they seem to be

Reflection and Refraction at the same time

You see both the reflection of the sky and the bottom of the lake.

Light splits: part of the sun light reflects of the water surface; other part goes into

water (and refracts), reflects off the bottom and then reaches observer eyes .

Simultaneous Reflection and Refraction in Windows

Why can you see yourself in a window?Glass always let sun light through and reflects some. If its dark inside, reflected light is all what you see.

Why can’t you see yourself in a window?When light comes from inside as well, it gives you additional picture on top of reflected from outside light.

Its all about which side is brighter.

Half-Silvered Surface of One-way mirrors

These glasses are coated with a very thin silver layer.Only half of the surface is coated, such as lots of light is reflected, but some light goes through. Observer is able to see what’s outside but is not seen himself.

Although some light goes from inside glasses, there is much more light that is refelcted back by glasses; so it

makes stronger mirror image of the outside object.

Half-Silvered Surface of One-way mirrorsThe "criminal suspect" does not see the detectives in the next room because the room in which the glass looks like a mirror is kept very brightly lit, so that there is plenty of light to reflect back from the mirror's surface.

The other room, in which the glass looks like a window, is kept dark, so there is very little light to transmit through the glass.

Mirages

A mirage is a naturally occurring optical phenomenon in which light rays are bent to produce a displaced image of distant objects or the sky.

Mirages show images of things which are elsewhere.

Cold air is denser than warm air and has therefore a greater refractive index. If the air near the ground is warmer than that higher up, the light ray bends in a concave, upward trajectory.

Inferior Mirages show objects lower than they are

You look down but see the sky down there… and think that it’s water

Inferior mirage, Mojave Desert

Whan air is colder at the bottom…

Light rays bend the other way:

You look up and see (getting light rays)…

What you see is not where you think it is!

Indeed, the object is much lower.

Superior mirage off the coast of Norway

Superior means ground objects are seen above

Superior mirage off the coast of California

3-Image Mirage, Antarctica

Superior mirage, Victoria, Canada

Fata Morgana of a ship, the image showing a number of frames

Fata Morgana constantly changing two ships’ appearances

Multiple-image Fata Morgana display, Farallon Islands, California

Fata Morgana squashing together and flattening mountains, Alaska

Fantastical Fata Morgana, Tetlin Hills, Eastern Alaska

Superior Mirages let us see objects behind horizon line

Normally you wouldn’t see beyond that point

Objects may be seen upside down

Cold airNot really warm airWarm airHot air