In case I'm wrong, the formula for energy of a photon is(adsbygoogle = window.adsbygoogle || []).push({}); E=hf.

OrE=hc/λ, becausef=c/λ.

Basically the second formula is just in case you don't know frequency so it crams the equation for that into the equation for energy.

When I useE=hc/λthe units I get are...

kg*m^{2}/s^{3}

What I did was... A photon of red light, has a wavelength of like 700nM, so...

(6.626×10^{-34}kg*m^{2}/s^{2}) (3x10^{8}m/s) / 7×10^{7}m

= 2.84×10^{19}kg*m^{2}/s^{3}

I thought the answer would be in Joules, which is kg*m^{2}/s^{2}, so I must be missing something... Why the extra unit of time.

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# Problem with units when using E=hv

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