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The 6563ÅH(alpha) line emitted by hydrog...

The `6563ÅH_(alpha)` line emitted by hydrogen in a star is found to be red-shifted by `15Å`. Extimate the speed with which the star is receding from the earth.

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We are given that:
`lamda=6563ÅrArrDeltalamda=15Å`
`lamda.=lamda+Deltalamda=6563+15=6578Å`
We are to calculate, speed of receding star (v)
Using relation:
`lamda.-lamda=v/(c)lamdarArrv=c((lamda.-lamda)/(lamda))=(6578-6563)/(6563)xx3xx10^(8)`
`v=15/(6563)xx3xx10^(8)=6.86xx10^(5)"m/s"`
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