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

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


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    $\begingroup$ Photons are a type of quantua. So the latter is more vague/general. $\endgroup$ Oct 4, 2022 at 15:09

1 Answer 1


"Number of photons" and "Number of quanta" are both dimensionless so

"quanta" cm$^{-2}$ s$^{-1}$ has the same units as "photons" cm$^{-2}$ s$^{-1}$.

But strictly, both expressions are wrong since:

$\log{x}= (x-1) - (1/2)(x-1)^2 + (1/3)(x-1)^3 - (1/4)(x-1)^4 + ...$

So the argument inside the logarithm should be unit-less.


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