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v_pino
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Homework Statement
Estimate the width of a 21cm spectral line produced by an interstellar cloud of atomic hydrogen with a temperature of 300K.
Homework Equations
From wiki (link below), I found an equation for full width at half maximum, relating it to Boltzmann constant, temperature T, mass m, and speed of light c.
http://en.wikipedia.org/wiki/Doppler_broadening
I used the mass of one hydrogen atom for m.
The Attempt at a Solution
I got 2.59x10^-4 cm but the answer should be 2.0x10^-4 cm.
Any idea where I went wrong? Is the "width" mentioned in the question equal to the full width at half maximum?
Thanks.