Problem with units when using E=hv

[Aspchizo]

In case I'm wrong, the formula for energy of a photon is E=hf.
Or E=hc/λ, because f=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 use E=hc/λ the units I get are...

kg*m²/s³

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

(6.626×10^-34kg*m²/s²) (3x10⁸m/s) / 7×10⁷m

= 2.84×10¹⁹kg*m²/s³

I thought the answer would be in Joules, which is kg*m²/s², so I must be missing something... Why the extra unit of time.

 

[Aspchizo]

Wow stupid, Planck's constant is J×s which is kg*m²/s

Well, everything else looks okay?

 

[mfb]

Check the signs of your exponents. Everything else looks right, if you fix your units.

 

[Aspchizo]

Ah right, ^-19

Thanks