1. The problem statement, all variables and given/known data Hey guys, I'm having trouble with a question covering magnectic field on a cilindrical conductor with a cilindrical cavity, here's the question: Consider a long cilindrical conductor with radius R1, with a cilindric cavity with radius a, in which R1>a. The axis of both cilinders are paralel, and are separated by a distance D≤R1-a. Assume that there's a uniform current density (J0) flowing through the cilinder's axis. Applying Ampere's law, use the concept of superposition of fields to calculate the resulting magnetic field on points a) inside the cavity b) outside the cavity but inside the conductor c) outside the conductor 2. Relevant equations Ampere's Law B=(μ0*i)/2πR 3. The attempt at a solution The attempt is attached below. But I couldn't figure out if the field inside the cavity is the field created by the surroundings of it or the field created by the whole conductor and avaliated inside the cavity. If it's the second option, how can I define it there?