Refraction through glass prism/Atmospheric refraction/scattering of light- HOTS Flashcards
give reason: disticnt hills appear blue
in the thick growth of trees, there are always tiny droplets of water present in the air. When white light passes through the moistured air, the water dorplets scatter the blue light since its of shorter wavelength.
give reason: smoke coming out of the chimney appears blue on a misty day
the small particles of smoke and dust scatter the blue light of shorter wavelength maximum when whitelight passes through it
give reason: motorists prefer using orange light than white light on a foggy dya
if they use white light, the tiny water droplets on a foggy day will scatter the blue light of shorter wavelength in a large amount and reduce visibility. If they use the orange light, it has larger wavelength and it doesn’t get scattered and gives good visibility to driver.
give reason: rescue workers wear coloured suits
coloured suits do not get scattered much and can travel long distance and it can be seen clearly in smoke, dust,fog etc
give reason: school bus is yellow
school bus is yellow since yellow has a longer wavelength it can travel long distance without getting scattered and is easily visible in smog,fog,mist etc
whyis red chosen as the danger signal
i) red has a longer wavelneght so it can travel longer distances.
ii) since v directly proportional to wavelnegth, red light travels faster
iii) due its longer wavelength, it does not get scattered a lot.
iv) it can be seen clearly through smoke/dust etc
a smoke coming from a chullah flickers. why
this is due to the atmospheric refraction caused by moving particles.
a cut diamond sparkles a lot. why
this is due to total internal reflection. diamond has a very high refractive index . The refractive index is inversely proportional to critical angle, the critical angle of diamond is very low. So whenever light strikes the diamond it exceeds the critical angle, and undergoes total internal reflection ,that is, all the light goes back to the diamond causing it to sparkle.
what is total internal reflection
i) this is a refraction phenomenon
ii) whenlight falls obliquely from a denser medium to a rarer medium, the light ray bends away from the normal.
iii) when the angle of incidence increases the angle of refraction increases since sin i / sin r is a constant.
iv) therefore for a particular angle of incidence the angle of refraction will be 90degrees. this angle of incidence is called the critical angle.
v) when the angle of incidence exceeds the critical angle, the light will go into the same medium.
sky appears greysih over cities having industrial units. WHY
the smoke and dust particles in the atmosphere in such cities, usually scatter light of longer wavelength like red/yellow/orange light than those of shorter wavelength. This is why the sky looks greyish.
why does the sky appear dark instead of blue to an astronaut
the blue colour of the sky is due to scattering of light by the dust particles,water droplets present in the atmosphere. these are called scatterers.
when the astronaut is in space,there is no atmosphere around him. Since there is no atmosphere, there are no scatterers to scatter sunlight. Sky appears dark.
