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SIR ,
ONE OF MY BOOK READS " THE COLOUR OF AN OBJECT IS ONLY DEPENDEND ON THE FREQUENCY OF THE SORCE AS LONG AS FREQUENCY IS CONSTANT THE COLOUR OF AN OBJECT CANNOT CHANGE "
COLOUR OF AN OBJECT IS NOT DEPENDENT ON THE WAVELENGTH OF THE SOURCE .
eg: IF A SOURCE OF RED LIGHT IS PLACED UNDERWATER THEN ABOVE THE SURFACE OF WATER THE COLOUR OF LIGHT DOESNOT CHANGE . AS IN REFRACTION FREQUENCY REMAINS CONSTANT BUT DESPITE CHANGE IN WAVELENGTH OF RED LIGHT FROM WATER TO AIR MEDIUM ITS COLOUR DOES NOT CHANGE . HENCE COLOUR IS NOT DEPENDENT ON WAVELENGTH .
MY DOUBT :
IF THE ABOVE IS TRUE THEN WHY DOES COLOUR OF RED LIGHT CHANGE TO GREEN LIGHT WHEN IT IS PASSED THROUGH A GLASS SLAB ? THS IS AN EXPERIMENTAL OBSERVATION STATED IN ANOTHER BOOK .
PLEASE EXPLAIN AND THANK YOU 
Comments (8)
" THE COLOUR OF AN OBJECT IS ONLY DEPENDEND ON THE FREQUENCY OF THE SORCE AS LONG AS FREQUENCY IS CONSTANT THE COLOUR OF AN OBJECT CANNOT CHANGE "
COLOUR OF AN OBJECT IS NOT DEPENDENT ON THE WAVELENGTH OF THE SOURCE .
eg: IF A SOURCE OF RED LIGHT IS PLACED UNDERWATER THEN ABOVE THE SURFACE OF WATER THE COLOUR OF LIGHT DOESNOT CHANGE . AS IN REFRACTION FREQUENCY REMAINS CONSTANT BUT DESPITE CHANGE IN WAVELENGTH OF RED LIGHT FROM WATER TO AIR MEDIUM ITS COLOUR DOES NOT CHANGE . HENCE COLOUR IS NOT DEPENDENT ON WAVELENGTH
It is absolutely correct and there is no doubt to this.
Colour i ofcourse frequency dependent not wavelength.
When the signal travels from one medium to another it changes its velocity and wavelength in the medium in such a way that its frequency is unchanged.
Thus the property of colour depends on frequency.
Now your problem is
IF THE ABOVE IS TRUE THEN WHY DOES COLOUR OF RED LIGHT CHANGE TO GREEN LIGHT WHEN IT IS PASSED THROUGH A GLASS SLAB ? THS IS AN EXPERIMENTAL OBSERVATION STATED IN ANOTHER BOOK .
It is because the red light is not purely monochromatic and is having a slight component of green in it (but it apparantly appears to be red, as a result of which when it passes through the glass prism (inspite of glass please check), then due to difference in refractive index the path of component changes and dispersion takes place.
YA AND MY BOOK SAYS NOTHING ABOUT GLASS SLAB OR GLASS PRISM IT ONLY SAYS THAT WHEN RED LIGHT IS PASSED THROUGH GLASS OF U=1.5 ONLY GREEN COLOUR IS SEEN.
IT SAYS ONLY GREEN LIGHT IS SEEN AND NO PART OF RED IS SEEN.
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buddy dun know abt this experiment ...
... red colour changes to green......
frequency is a property of light source and thus is constant....... whn light passes thru a denser medium its speed decreases so wavelegth must cange.......
but colour is in fact an outcome of energy wave= hf..... and that doesnt change.... so it mustnt change.... maybe the buk has mentioned abt somethng more done in experiment....
atbest wat i can thnk of is little absorption of energy by glass slab... and this ud lead to excitation of electronsand while falling of releasin energythus increasin it... thus changing frequency.... and colour......
but this realy is a stupid illogical ans.. if ur considerin glass...........
dun know........ see the experiment again..... i thnk somethng is wrng thre
Cheers!!!!!