$\frac{dL}{dt}=N$.
In a working on electrodynamics:
It says this implies $\int_{0}^{T}\frac{dL}{dt}dt=\int_{0}^{L}dL =L=\int_{0}^{T}dN$
I've been staring at the last equality for an hour in an attempt to understand how that came about but to no avail.
Any clarification is appreciated.