CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2002

  • question_answer
    \[{{\upsilon }_{O}}\]and\[{{\upsilon }_{E}}\]represent the velocities, \[{{\mu }_{O}}\]and \[{{\mu }_{E}}\]he the refractive indices of ordinary and extraordinary rays for a double refracting crystal. Then:

    A) \[{{\upsilon }_{O}}\le {{\mu }_{O}}\le {{\mu }_{E}},\]if the crystal is quartz

    B)  \[{{\upsilon }_{O}}\ge {{\upsilon }_{E}},{{\mu }_{O}}\le {{\mu }_{E}},\]if the crystal is calcite

    C)  \[{{\upsilon }_{o}}\ge {{\upsilon }_{E}},{{\mu }_{o}}\ge {{\mu }_{E}},\]if the crystal is quartz

    D) \[{{\upsilon }_{1}}\le {{\upsilon }_{E}},{{\mu }_{o}}\ge {{\mu }_{E}},\]if the crystal is calcite.

    Correct Answer: D

    Solution :

    In double refraction light rays always split   into   two,   ordinary   and extraordinary.  O-waves has same velocity in all direction but E-waves has different velocity in different directions. Along optic axis O and E waves have same velocity uniaxial crystal are of two types \[-\,\text{ve}\]and \[+\,\text{ve}\text{.}\] \[-\,\text{ve}\]crystal is calcite for this \[{{\mu }_{E}}<{{\mu }_{O}}\]                 \[\therefore \]  \[{{\upsilon }_{e}}>{{\upsilon }_{O}}\]                 \[(+\,\upsilon e)\]crystal: for quartz crystal \[{{\mu }_{E}}>{{\mu }_{O}}\] \[\therefore \]  \[{{\upsilon }_{O}}>{{\upsilon }_{E}}\]


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