# Units conversion - quanta/cm$^2$/s and photons/cm$^2$/s

Can you tell me if there is any difference between these 2 units?

$$\log \mathrm{quanta/cm^2/s}$$ vs $$\log \mathrm{photons/cm^2/s}$$

Thanks

"quanta" cm$$^{-2}$$ s$$^{-1}$$ has the same units as "photons" cm$$^{-2}$$ s$$^{-1}$$.
$$\log{x}= (x-1) - (1/2)(x-1)^2 + (1/3)(x-1)^3 - (1/4)(x-1)^4 + ...$$
• Note that $\log(a/b)\equiv\log(a)-\log(b)$, so it is possible for units to be present in the argument of logarithms, though care needs to be taken (I believe there is a PSE post on the use of units in log) – Kyle Kanos Jul 3 at 14:33