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Effect of Total Internal Reflection
Let us now discuss some of the effect of total internal reflection. Mirage in deserts and sparkling of diamonds are the some of the effects of the total internal reflection.
Mirage in deserts
Mirage is an optical illusion seen very often in deserts due to which an observer sees a inverted images of distant objects. The observer thinks that the inverted image of the far of object is the reflection of the object in water. Although no water exist there. Let us say how this happens.
In deserts as the sand gets heated the lower layer of the air becomes very hot and the uppers layers are comparatively cooler. A light ray coming downwards from any object passes through layers of air of gradually decreasing density. At each layer refraction take place and the light rays bends away from the normal. Angle of incidence continues to increase until at a certain layer the ray is incident at the angle greater than the critical angle of the air with respect to the next layer of air. At this interface the light rays suffers total internal reflection and proceeds upwards from the rarer to the denser layer of the air. The whole path of the ray is therefore concave as shown here.
Due to this the observer will see an inverted image of the object. The observer thinks that there is a pool of the water from the formation of the image.
A similar phenomenon is observed on roads. On hot summer days it is due to total internal reflection that the surface of hot tires roads seeing to wet and shine.
Sparkling of diamonds
A diamond sparkles as the rays of light suffered total internal reflection has its various faces'. Let us say how this happens.
The critical angle for the ray of light traveling from diamond to air is very low about 24 degrees. Therefore, most of the incident rays suffer from the total internal reflection. Moreover the diamonds are usually cuts with their faces in such a way that once a ray of light enters it. It suffers from total internal reflections at various phases before it has any chance to emerge. Whenever the angle of incidence at any phase is less than 24 degrees the light comes out from it and the diamond appears to be bright. Thus a ray of light on entering the cut diamond literally gets trapped within it for sometimes and causes it to sparkle.
Effect of Total Internal Reflection
Let us now discuss some of the effect of total internal reflection. Mirage in deserts and sparkling of diamonds are the some of the effects of the total internal reflection.
Mirage in deserts
Mirage is an optical illusion seen very often in deserts due to which an observer sees a inverted images of distant objects. The observer thinks that the inverted image of the far of object is the reflection of the object in water. Although no water exist there. Let us say how this happens.
In deserts as the sand gets heated the lower layer of the air becomes very hot and the uppers layers are comparatively cooler. A light ray coming downwards from any object passes through layers of air of gradually decreasing density. At each layer refraction take place and the light rays bends away from the normal. Angle of incidence continues to increase until at a certain layer the ray is incident at the angle greater than the critical angle of the air with respect to the next layer of air. At this interface the light rays suffers total internal reflection and proceeds upwards from the rarer to the denser layer of the air. The whole path of the ray is therefore concave as shown here.
Due to this the observer will see an inverted image of the object. The observer thinks that there is a pool of the water from the formation of the image.
A similar phenomenon is observed on roads. On hot summer days it is due to total internal reflection that the surface of hot tires roads seeing to wet and shine.
Sparkling of diamonds
A diamond sparkles as the rays of light suffered total internal reflection has its various faces'. Let us say how this happens.
The critical angle for the ray of light traveling from diamond to air is very low about 24 degrees. Therefore, most of the incident rays suffer from the total internal reflection. Moreover the diamonds are usually cuts with their faces in such a way that once a ray of light enters it. It suffers from total internal reflections at various phases before it has any chance to emerge. Whenever the angle of incidence at any phase is less than 24 degrees the light comes out from it and the diamond appears to be bright. Thus a ray of light on entering the cut diamond literally gets trapped within it for sometimes and causes it to sparkle.
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