(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

I want to convert wavenumbers into wavelength. The wavenumber is 400cm-1 and i used the expression v=vbar*c to get the frequency in Hz to be 1.2*10^13, I also remembered to convert c into cm/s so that frequency is in its SI units (seconds). I then simply thought that I could use the expression lambda=c/v to get the answer i require and then multiply that answer by 1*10^9 to get my answer in nm instead of ms. I know the answer should be

2500nm but i get 25000nm. Why do i have this factor of 10? where did it come from?

2. Relevant equations

i began with vbar=400 cm-1

so then i said that

v=vbar*c

v=400*3*10^10

v=1.2*10^13 Hz

I then said that

lambda nm=(c/v)*1*10^9

lambda=(3*10^8/1.2*10^13)1*10^9

lambda = 25000 nm when it should be 2500nm or 2.5um

3. The attempt at a solution

Please see above

I know this forum is used mainly by graduates who set eachother calculus based challenges but any help for a simple folk like me would be much appreciated.

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# Homework Help: A question relating to frequency i think a 10 year could do this but i cant lol

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