MGIMS WARDHA MGIMS WARDHA Solved Paper-2009

  • question_answer
    The observed wavelength of light coming from a distant galaxy is found to be increased by 0.5% as compared with that coming from a terrestrial source. The galaxy is

    A)  stationary with respect to the earth

    B)  approaching the earth with velocity of light

    C)  receding from the earth with velocity of Light

    D)  receding from the earth with a velocity equal to \[1.5\times {{10}^{6}}m/s\]

    Correct Answer: D

    Solution :

    \[\frac{\Delta \lambda }{\lambda }=\frac{v}{c}\] Now,     \[\Delta \lambda =\frac{0.5}{100}\] \[\Rightarrow \]               \[\frac{\Delta \lambda }{\lambda }=\frac{0.5}{100}\] \[\therefore \]  \[v=\frac{0.5}{100}\times c=\frac{0.5}{100}\times 2\times {{10}^{8}}\] \[=1.5\times {{10}^{6}}m/s\] Increase in\[\lambda \]indicates that the star is receding.


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