please help me with this problem with full details,thank you! For this problem y
ID: 2273129 • Letter: P
Question
please help me with this problem with full details,thank you!
For this problem you may assume the Earth is not moving. Also, you do not need to do this problem for each individual spectral line. Consider the following spectra below. The first spectrum provides the scale for the visible spectrum (i.e. it is the spectrum taken from a stationary white light bulb in the laboratory), the second spectrum is taken from a stationary hydrogen lamp in the laboratory, and the third spectrum is taken from a star (made up of hydrogen). Is the star approaching or receding from the Earth? Explain. Calculate an approximate radial speed of the star.Explanation / Answer
a)
it is approching because we see that the wavelengthes of the star are smaller than the white light bulb.
b)
lamda_source = (lamda_observed) * sqrt((1+v/c)/(1-v/c))
==> (1+v/c)/(1-v/c) = ((lamda_source)/(lamda_observed))^2
==> (1+v/c)/(1-v/c) = (460/452)^2
==> (1+v/c)/(1-v/c) = 1.0357
==> v/c = 0.01754
==> v = 0.01754 * 3e8 = 5.26 x 10^6 m/s
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