Refraction Of Light Notes r2j29

Reflection of light by www.ExamFear.com Bending of light when it es from one medium to another is known as Refraction. But, what is medium? A medium is a substance through which light es like water, air, kerosene, turpentine etc. The ray of light that is incident on Highlight the following in the surface is the Incident Ray.

Please note that the surface here script: 1. Incident Ray refers to the surface between the 2. Refracted Ray two media. 3. Normal to the ray that bent on entering the other medium is the Refracted surface 4. Angle of Ray. Normal to the surface refers to an Incidence 5. Angle of imaginary line perpendicular to the surface.

Refraction The angle between the incident ray and the normal to the surface is termed as the Angle of Incidence. Angle of Refraction is the angle between the refracted ray and the normal to the surface. Well.. There are certain rules that govern the phenomenon of Refraction. Rule 1: When a ray of light es from a rarer medium to a denser one, it bends towards the normal. Rule 2: When a ray of light es from a denser medium to a rarer one, it bends away from the normal. Now that we are clear with What is Refraction, Let us concentrate on the Laws of Refraction. There are 2 laws of Refraction. First Law: The incident ray, the refracted ray and the normal all lies on the same plane. Second Law: Ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant for a specific light of a specific colour and for a specific pair of media.

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Before going into the discussion of Refractive Index, let us discuss something quite interesting..

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Let us now discuss the term ‘Refractive Index’.

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A question that had remained unanswered till this point is why does refraction occur or in other words why does the light ray bend while ing from one medium to another. The reason behind this is that the velocity of light is different in different media. And Refractive Index plays a role here. Refractive Index of medium 2 with respect to medium 1 = v1/ v2; where v1 is the velocity of light in medium 1 and v2 is the velocity of light in medium 2. Similarly, Refractive Index of medium 1 with respect to medium 2 = v2/v1. Now that we are aware of the basic knowledge of refraction, Let us look at a few advanced examples from day to day life.

Have you ever thought why do stars twinkle??? Or do the stars really twinkle?? No, they don’t. They just appear to twinkle. Why?? Of course due to Refraction. Let’s discuss the same in detail. The light rays from the stars es through layers of air of different densities. In other words it travels from rarer to denser medium and thus suffers refraction. The rays keep bending towards normal again and again. Also, due to the movement of the air and the convection currents the densities of the layers of air keep changing. As a result of this, the position of the star as viewed by us keeps changing which gives an impression of twinkling. Well.. Now we have come to an end of the basic idea of Refraction. Exercise your brain with a small question.. Go back to the ‘Introduction’ page of the topic. Can you now answer why did the print behind the vessel appear raised???

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Of course you know the answer now!!!!

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