Question

Explain optics chapter briefly.

Answer 1

Optics is the branch of physics which involves the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it.Optics usually describes the behaviour of visible, ultraviolet, and infrared light. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties

Answer 2

Optics is the study of light
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light can be studied  an wave or particle both combined together we call it was the dual nature of light
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some of the important terms on light
1)reflection
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the bouncing back of light when it hits an reflecting surface is called as reflection

the two laws of reflection are 

1)The incidenct ray, the reflected ray, and the normal to at the point of incidence all lie in the same plane.

2)The angle of incidence is equal to  the angle of reflection.
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refraction
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the bending of the light when it passes through and refracting surface is called as refraction

the two laws of refraction are 

1)the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant for a light of given color and wavelength

2)The angle of incidence is equal to  the angle of refraction
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formation of rainbow
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A rain bow is formed when the sunlight passes through the raindrop and inside the raindrop there will be total internal refraction and the light undergoes dispersion dude to which the light gets spitted into its 7 different constituents resulting in the formation of the rainbow before that the light undergoes refraction 2 times.
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Twinkling of stars
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Stars have to travel a very large distance before reaching the earth and the refractive index of the atmosphere wont be same everywhere and the density keeps changing resulting in the twinkling of stars.
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blue colour of sky
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The color of sky is due to the property of dispersion of light 

the white light of the colour before reaching the earths surface gets dispersed into its 7 components VIBGYOR 

the molecules present in the atmosphere are capable of scattering only the light with shortest wavelength and hence red light wont get scattered

As the light that we get from sun is white in color and due to atmospheric refraction splitting up of white light takes place and the light with longest wavelength gets lost in the space and blue and violet has shortest wavelength but the intensity of blue will be much more than that of violet which makes us see the sky blue in colour and our eyes are more sensitive to blue light
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Mirages
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they are the optical illusions seen in hot summer days because of total internal reflection and on a hot day the air below the ground will have more density when compared to that above the ground and the light undergoes TIR before it reaches our eye which will make the ground appear like water reflecting trees
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Apparent position of sun
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the light from sun will travel from vaccum to air i.e rarer to denser which makes it bend towards the normal which makes the sun to be seen even before it it rises or sets. We see the sun 2 mins before the actual sunrise and 2 mins after the actual sunset
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