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The spectral line emitted by a star, known to have a wavelength of 6500 Å, when observed in the laboratory appears to have a wavelength 6525 Å. What is thespped of the star in the line of light relative to the earth fro receding or approaching? |
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Answer» `1.154 xx 10^(6) ms^(-1)` receding `Delta lambda = lambda - lambda. = 6525 - 6500` ` = 25 Å(+ ve)` Doppler.s shift `Delta lambda = -(v)/(C) lambda` `therefore v = -(Delta lambda)/(lambda) c = - (25)/(6500) xx 3 xx 10^(8)` ` = -1.154 xx 10^(6) ms^(-1)` `-ve` sign indicates that STAR is receding from the earth. |
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