A nutshell view of the phenomenon of REFRACTION..

REFRACTION

Speed of Light &amp; Optical Density

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Absolute & Relative refractive index

Relative refractive index:&nbsp;When light travels from one medium to another medium, then the refractive index is known as the relative refractive index. Absolute refractive index:&nbsp;When light travels from vacuum to another medium, then the refractive index is known as the absolute refractive index.

Check out this video for difference between absolute and relative refractive index

When light travels in medium other than the vacuum, the atoms of that medium continually absorb and re-emit the particles of light, slowing down the speed light. The ratio between the speed of light in medium to speed in a vacuum is the refractive index.&nbsp;

-Refractive index is also referred to as refraction index or index of refraction. -The speed of light in a medium depends on the properties of the medium. -In electromagnetic waves, the speed is dependent on the optical density of the medium. Refractive Index Formula -The refractive index is dimensionless. -It is a number that indicates the number of times slower than a light wave would be in the material than it is in a vacuum. -The refractive index is represented by symbol n, is the velocity of light in vacuum divided by the velocity of light in a medium.&nbsp;

Refractive Indices of Different Materials

Refraction is the bending of a wave when it enters a medium where its speed is different. The refraction of light when it passes from a fast medium(rarer) to a slow medium(denser) bends the light ray toward the normal to the boundary between the two media. The amount of bending depends on the indices of refraction of the two media and is described quantitatively by Snell's Law. The bending of refraction can be visualized in terms of Huygens' principle. As the speed of light is reduced in the slower medium, the wavelength is shortened proportionately. The frequency is unchanged; it is a characteristic of the source of the light and unaffected by medium changes.

Laws of refraction state that: 1)The incident ray refracted ray, and the normal to the interface of two media at the point of incidence all lie on the same plane. 2)The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant. This is also known as Snell’s law of refraction.

SNELL'S LAW "The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant."

Refraction of Light

For more explanation visit this youtube  channel

Speed of light &amp; Optical Density . . . . . . . . . . . Refraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -Refraction in different media . . . . . . . . . . . . -Refraction laws . . . . . . . . . . . . . . . . . . . . . . . -Refractive Index . . . . . . . . . . . . . . . . . . . . . . . . -Relative &amp; Absolute refractive index . . . . . . . Total Internal Reflection . . . . . . . . . . . . . . . . . . -Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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What are the conditions for Total Internal Reflection?

Consider the following situation. A ray of light passes from a medium of water to that of air. Light ray will be refracted at the junction separating the two media. Since it passes from a medium of a higher refractive index to that having a lower refractive index, the refracted light ray bends away from the normal. At a specific angle of incidence, the incident ray of light is refracted in such a way that it passes along the surface of the water.Here the angle of refraction is 90 degrees. When the angle of incidence is greater than this angle, the incident ray is reflected back to the medium. We call this phenomenon total internal reflection.

-The light ray moves from a more dense medium to a less dense medium. -The angle of incidence must be greater than the critical angle.

Critical angle: It is defined as the angle of incidence that provides an angle of refraction of 90-degrees. Make particular note that the critical angle is an angle of incidence value. For the water-air boundary, the critical angle is 48.6-degrees. For the crown glass-water boundary, the critical angle is 61.0-degrees. The actual value of the critical angle is dependent upon the combination of materials present on each side of the boundary. Θcrit= sine-1&nbsp;(nr/ni) = invsine (nr/ni)

Refer the video for detailed explanation

The Critical Angle and Total Internal Reflection - IB Physics

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-The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. -Its exact value is defined as 299792458 metres per second (approximately 300000 km/s, or 186000 mi/s). -It is exact because, by international agreement, a metre is defined as the length of the path travelled by light in vacuum during a time interval of 1⁄299792458 second. -According to special relativity, c is the upper limit for the speed at which conventional matter, energy or any signal carrying information can travel through space.

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Sunlight takes about 8 minutes 17 seconds to travel the average distance from the surface of the Sun to the Earth.

It is the measure of speed of light through a medium

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➊ Property of a transparent material. ➋ Measure of speed of light through the material ➌ Speed of light decreases in a denser medium, while it increases in a rarer medium ➍ The light passing via an optically dense medium bends towards the normal ➎ The light passing via an optically rarer medium bends away from the normal ➏ Therefore, "the extent to which any optically dense medium bends transmitted light rays towards or away from the normal is called its optical density."

Warp black

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Its not an optical illusion, it just looks like one!!

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