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What speed should a galaxy move with respect to us so that the sodium line at 589.0 nm is observed at 589.6 nm? |
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Answer» Solution :Since `v LAMBDA=c, (Deltav)/(v)=-(Deltalambda)/(lambda)""("for small changes in vand "lambda)` . For `DELTA lambda=589.6-589.0=+0.6nm` We get `["USING Eq. "(10.9)]` `(Deltav)/(v)=-(Delta lambda)/(lambda)=-(v_("radial"))/(c)` or, `v_("radial")~=+c((0.6)/(589.0))=+3.06xx10^(5)ms^(-1)` `=306km//s` THEREFORE, the galaxy is moving away from US |
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