# Faraday's Law in the transient solution of Rl circuit

Consider RL circuit consisting of a battery , resistance , inductor , and switch .all components are in series .

If we close the switch at time t =0 the current will build up until reaching a maximum .now i want to put the differential equation that discribes the circuit while the current is building up and i know from walter lewin lectures that i have to use Faraday's law not kirchhoff's loop rule because we have nonconservative electricfield .

Walter lewin derives the differential equation as follows

Closed loop integral of (E.dl)=-Ldi/dt

IR - v = -Ldi/dt

What baffles me is what kind of electric field do we mean in the above formula ?do we mean the nonconservative electricfield only or do we mean the superposition of conservative and nonconservative electricfield ?