AMU Medical AMU Solved Paper-2015

  • question_answer
    A glass slab of thickness 8 cm contains the same number of waves as 10 cm of water when both are traversed by the same monochromatic light. If the refractive index of water is 4/3, the refractive index of glass is

    A)  3/4                                       

    B)  3/5

    C)  5/3                                       

    D)  5/4

    Correct Answer: C

    Solution :

                     Let \[{{\lambda }_{g}}\]  and \[{{\lambda }_{w}}\] be the wavelengths in glass and water respectively. Number of waves in glass slab of thickness \[8\,cm=\frac{8}{\lambda g}\]S Number of waves in water. According to the question, (10 cm) \[=\frac{10}{\lambda w}\]                                 \[\frac{8}{{{\lambda }_{g}}}=\frac{10}{{{\lambda }_{w}}}\] \[\Rightarrow \]                               \[\frac{{{\lambda }_{w}}}{{{\lambda }_{g}}}=\frac{5}{4}\] We have \[{{\mu }_{g}}=\frac{C}{{{v}_{g}}}\] and \[{{\mu }_{w}}=\frac{C}{{{V}_{w}}}\]                 \[\frac{{{\mu }_{g}}}{{{\mu }_{w}}}=\frac{{{v}_{w}}}{{{v}_{g}}}=\frac{n\,{{\lambda }_{w}}}{n\,{{\lambda }_{g}}}=\frac{{{\lambda }_{w}}}{{{\lambda }_{g}}}\]                 \[{{\mu }_{g}}=\frac{{{\lambda }_{w}}}{{{\lambda }_{g}}}\times {{\mu }_{w}}=\frac{5}{4}\times \frac{4}{3}=\frac{5}{3}\]


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