Tuesday, May 14, 2019

Kerala PSC Physics - Light (Part- I)

Light is a electromagnetic radiation that occupies certain position in electromagnetic spectrum.

    • Study of Light : Optics
    • The substances that will not pass light through them are called : Opaque Substances
    • The substances that allows light to pass through them are called : Translucent Substance
    • The substance that allows light to partially pass through them are called : Translucent Substance 
    • Speed of Light was first calculated by : Ole Christensen Roemer
    • Speed of light : 3 X 108 m/s
    • In the equation, E = mc2, 'c' stands for : Velocity of Light
    • Time taken by light to reach Earth from Sun : 8 Minutes and 20 Seconds (500 Seconds)
    • Time taken by light to reach Earth from Moon : 1.3 Second
    • The light has maximum speed in : Vacuum
    • Speed of light is inversely proportional to the density of the medium
    • The scientist who found that the speed of light is maximum in vacuum is : Leon Foucault
    • Unit used for the measurement of wavelength of light : Angstrom
    • The medium in which the speed of light is minimum : Diamond
    • The light has least density in vacuum and maximum density in diamond
    • The particles that travel faster than light : Tachyons
    • Indian scientist who discovered Tachyons : E C G Sudharsanan
    • The word Tachyons was first used by the scientist : Gerald Feinberg
    • The distance traveled by the light in one year is called : Light Year
    • Light Year is a unit of : Distance
    • Light Year is used to measure the distance between stars
    • One Light Year is : 9.46 X 1012  Km
    • Smallest unit used to measure distance in space is : Astronomical Unit
    • One Astronomical Unit (AU) is : 1.5 X 108 Km
    • The distance between Earth and Sun is : 1 AU
    • One parsec is : 3.26 Light Years
    • The scientist who discovered light is an electromagnetic wave : Heinrich Rudolph Hertz
    • The position (wavelength) of visible light in electromagnetic spectrum : 400 nm to 700 nm
    • Which electromagnetic wave carries more energy : Gamma Rays
    • Optical telescope detects : Visible light

     Light - Colours 

    • Primary colours are : Red, Green and Blue
    • Secondary Colours are : Magenta, Yellow and Cyan
    • Red + Blue = Magenta
    • Red + Green = Yellow
    • Green + Blue = Cyan
    •  The combination of primary and secondary colour that forms white light : Complimentary Colour
    • Red + Cyan = White
    • Green + Magenta = White
    • Blue + Yellow = White
    • Visible light consists of seven colours : VIBGYOR
    • VIBGYOR - Violet, Indigo, Blue, Green,Yelow, Orange and Red
    • The colour at the centre of the rainbow: Green
    • The Red colour in rainbow is seen at an angle : 42.8 o
    • The Violet colour in rainbow is seen at an angle : 40.8
    • The shape of the rainbow when looked from outer space : Circle
    • Violet has least wavelength
    • Red has maximum wavelength
    • Red has minimum frequency
    • Violet has maximum frequency
    • Colour that absorbs all other colour : Black
    • Colour that reflects all other colour : White
    • Colour that absorbs maximum heat : Black
    • Colour that absorbs minimum heat : White
    • Rainbow appears in the opposite direction of Sun
    • The colour that appears above the rainbow : Red
    • The colour that appears below the rainbow : Violet
    • The colour of the sky when looked from outside of the earth's atmosphere : Black
    • The Red flower when looked through Blue glass appears in : Black
    • The colour of the green leaf in red light : Black
    • The colour used in danger sign boards : Red
    • The colour used in danger sign boards in laboratory : Yellow
    • The colour of light used in vehicles during snowfall : Yellow
    • The most sensitive colour to human eye : Yellow
    • The blue colour of the sky was explained by : Lord Rayleigh
    • The  blue colour of the sky and the yellow colour of the setting sun is due to the phenomenon of : Rayleigh Scattering
    • Blue colour of the sea was explained by : C V Raman
    •  The colour of Nitrogen Vapour Lamp is : Red
    • The colour of Sodium Vapur Lamp is : Yellow
    • The colour of Neon Vapour lamp is : Orange
    • The colour of Chlorine Vapour Lamp is : Green
    • The colour of Hydrogen Vapour Lamp is : Blue
    • The colour of Mercury Vapour lamp is : White
    •  Corpuscular theory was explained by : Issac Newton
    • The corpuscular theory states that light is made up of tiny particles called ‘corpuscles’ that always travel in a straight line.
    • The scientist who proposed that the sunlight consists of seven colours : Issac Newton
    • Wave theory of light is put forward by : Christian Huygens
    • Electromagnetic Theory of light was put forward by : James Clerk Maxwell
    • The process of bouncing back of light when a beam of light falls on a surface : Reflection

     Light - Refraction

    • Bending of light ray when light travels from one medium to another : Refraction
    • The stars twinkle due to : Refraction
    • The phenomenon which causes the optic illusion of Mirage : Refraction
    • Working principle of periscope : Reflection and Refraction
    • Snell's law is associated with : Refraction
    • Glass prism produces spectra by : Refraction
    • Refractive Index, n = c/v        Where 'c' is the velocity of light in vacuum and 'v' is the velocity of light in medium. 

    Medium Refractive Index (n)
    Vacuum 1
    Ice 1.31
    Water 1.33
    Diamond 2.42
    Glass 1.52

     Light - Total Internal Reflection

    •  Sparkling of diamond is due to : Total Internal Reflection of Light
    • Working principle of Optic Fibre is : Total Internal Reflection
    • Sparkling of water droplet is due to : Total Internal Reflection
    • Inventor of Optic Fibre : Narinder Singh Kapany

     Light - Dispersion

    • Splitting of light into its constituent colours is called : Dispersion
    • Device used to slit white light in to its constituent colours : Prism
    • Scientist who explained Dispersion : Issac Newton
    • Phenomenon that occurs in the rainbow : Refraction, Dispersion and Total Internal Reflection

     Light - Interference

    • The process of distribution of light energy when two or more light waves superimposes is called  : Interference
    • The different colours in soap bubbles is due to  : Interference
    • The different colours on soap bubbles is due to : Interference
    • The colours that appear on the upper layer of oil spread on road is due to : Interference
    • The technique of recording and reproducing three dimentional images based on the principle of  interference of light : Holograph
    • The three dimentional images produced through holograph are called : Holograms
    • The interference pattern using light waves was first observed by : Thomas Young

     Light - Diffraction

    • The bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture is called : Diffraction
    • The projector in the film theatre works on the principle of  : Diffraction
    • The rings seen around the sun is due to : Diffraction
    • The colours fringes seen on CD is due to : Diffraction

    Light - Polarisation

    • The process of converting the vibration of a transverse wave into a particular direction : Polarisation
    • Turmalin is a naturally polarising material 
    • Nicol prism is a Polaroid 

    Related Post :

    1. Physics : (Light Part - II)


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