Emerald Bridal Fashion Beautiful Jewellery Collection 2013 19

Emerald Bridal Fashion Beautiful Jewellery.
By Aamir mannan.
13.REFRACTIVE INDEX AND ITS MEASUREMENT

There is a point here which may usefully cleared up since it causes confusion to students. what is known as the critical angle of a stone is the angle at which rays of light passing from the stone into air are refracted at 90 to a line prependicular to the surface between the two media . rays striking the inside surface of a stone at angle creater than this critical angle cannot emerge, and are totally reflected back into the stone. here the stone is the denser medium, and the higher the refractive index of the stone is the smaller is its critical angle. in the case of refractomemter the principle is exactly the same, but here the glass of the refractometer is the denser medium, and the stone is the rarer medium. thus, in this case the higher the refractive index of the stone the greater is the critical angle between it an the glass of the instrument.