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What speed should a galaxy move with respect us to that the sodium line at 589.0nm is observed at 589.6nm? |
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Answer» Solution :Since `v lambda= c`, `(TRIANGLE v)/(v)= -(triangle lambda)/(lambda)` (for small changes in v and `lambda`). For `triangle lambda= 589.6-589.0= +0.6nm` we get [using Eq. (3.9)] `(triangle v)/(v)= -(triangle lambda)/(lambda)= (-v_("raidial"))/(v)" or, "v_("RADIAL") cong +c ((0.6)/(589.0))` `= +3.06xx 10^(5)ms^(-1)= 306 KM"/"s` Therefore, the galaxy is movingaway from US. |
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