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JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2004

  • question_answer
        The k line of singly ionised calcium has a wavelength of 393.3 nm as measured on earth. In the spectrum of one of the observed galaxies, this spectral line is located at 401.8 nm. The speed with which the galaxy is moving away from us, will be :

    A)  6480 km/s

    B)  3240 km/s

    C)  4240 km/s

    D)  none of these

    Correct Answer: A

    Solution :

                    Here:     \[{{\lambda }_{0}}\]= 393.3 nm \[\lambda \]= 401.8 nm Red shift,\[z=\frac{\lambda -{{\lambda }_{0}}}{{{\lambda }_{0}}}\] \[=\frac{401.8-393.3}{393.3}\] \[=\frac{8.5}{393.3}=0.0216\] Now \[z=\frac{\upsilon }{c}\]then \[\upsilon =zc=0.0216\times 3\times {{10}^{8}}\] \[=6.48\times {{10}^{6}}m/s\] \[=6480km/s\]


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