# Why is $\langle \text dp/\text dt\rangle$ zero for electrons in steady state?

While reading the Drude theory of transport in metals from the Oxford Solid state basics, I noticed when deriving the conductivity of the metal using Drude theory, to simplify the calculation the author said that we'd be doing it for steady state and that in steady state, $$\langle \text dp/\text dt\rangle= 0$$. I don't really understand why that is. If I'm applying an external electric field, and if because of this there is an electrical current in the metal due to this, then how is the net rate of change of momentum of the electrons zero?

• In circuits connected to a battery does the current keep in increasing? – Aaron Stevens Sep 13 at 11:26
• In "steady state" how is the momentum of the collection of electrons changing with time? – Jon Custer Sep 13 at 13:20
• $\langle\mathrm dp/\mathrm dt\rangle=0\neq p=0$. – Kyle Kanos Sep 17 at 11:19