question_answer

Refractive indices of glass for violet yellow and red colours are \[{{\mu }_{V}},{{\mu }_{\Upsilon }}\]and \[{{\mu }_{R}}\]respective! Write these in decreasing order of value. Justify your answer.                        

Answer:

                The refractive index \[\mu \] of a material  wavelength \[\lambda \] is given by the Cauchy's relation, \[\mu =a+\frac{b}{{{\lambda }^{2}}}+\frac{c}{{{\lambda }^{4}}}\] where a, b and c are constants, the values of which depend on nature of the material. As  \[{{\lambda }_{V}}<{{\lambda }_{\Upsilon }}<{{\lambda }_{R}}\] Hence \[{{\mu }_{V}}>{{\mu }_{\Upsilon }}>{{\mu }_{R}}\]