1. The problem statement, all variables and given/known data A cylindrical parallel plate capacitor of radius R is discharged by an external current I. The total electric field flux inside the capacitor changes at a rate dΦe/dt = I/ ε0. What is the strength of the resulting magnetic field B(r, I) inside the capacitor at a radial distance r from the centre axis? Start the answer with Maxwell’s extension to Ampere’s law. 2. Relevant equations So using the line integral ∫B⋅dl= μ0 (I + Id ) 3. The attempt at a solution you get B⋅2πr= μ0 (I + Id ) However i don't understand what I and Id are? I have the equation Id= ε0 dΦe/dt however i don't understand why this is true or where this takes me?