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Calculating the energy emitted by a photon from a transition Watch

1. I'm not sure if it's me or my mark scheme that is wrong so a 3rd opinion would be appreciated!

I know that the wavenumber = 1340.5cm-1

I then used the equation E=hcv

h = Planck's constant (Js)
c= Speed of light (ms-1 )
v = 1340.5cm-1 = 13.405 m-1

E = 2.66x10-24 J = 1.7 x 10-5 eV

However my mark scheme says that E = 0.17eV / 2.66x10-20 J

Where am I going wrong?
2. You probably forgot to change the wavenumber from cms to metres?

EDIT: no you did that sorry
3. So am I right?
4. Try changing your wavenumber to wavelength, then convert it to metres, then change it back.
5. It's E=hf btw, or E=h(c/wavelength)

I converted the wavenumber to wavelengths in the correct units and I got the right answer, try it again.
6. Yep that gets the right answer. The problem is the cm-1

this line was wrong...

v = 1340.5cm-1 = 13.405 m-1

Strictly speaking it's...

v = 1340.5cm-1 = 1340.5 (c)-1 m-1 = 1340.5 (1/100)-1 m-1= 1340.5 (100) m-1 = 134,050 m-1
7. Thank you halfoflessthan50p! That made it clear.

(Original post by GlibByNature)
It's E=hf btw, or E=h(c/wavelength)
Thank you but it's definintely E=hcv, just that the v is actually the v symbol with this wobbly line on top: ˜ for wavenumber but I couldn't find it to copy/paste (Because 1/ wavelength = v)

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