# Inconsistency in two equations for Planck law given by professor

I know there are a variety of questions about this topic but I have been searching the internet for a long time and couldn't find a proper answer. The question is simple:

I saw the following formula in my professor's notes for Planck's formula:

$$I(\nu,T) = \dfrac{2\pi h \nu^3}{c^2} \dfrac{h\nu}{e^{h\nu/kT}-1} .$$

However, wherever I look I have seen it in a form such that:

$$I(\nu,T) = \dfrac{2\pi h \nu^3}{c^2} \dfrac{1}{e^{h\nu/kT}-1} .$$

Simply without a $$h\nu$$ term. Why? What is the difference exactly? Was my professor just make a mistake?

• I don’t recognize the first formula. My guess is that it’s a mistake. I suggest asking your professor. – G. Smith Sep 17 at 23:06
• I will, as soon as possible. Then I will update it. – Ekrem Sep 18 at 21:04
• What is $I$ in the first place? Intensity of what? Power? Energy per frequency? – Cham Oct 4 at 17:15