1. The problem statement, all variables and given/known data A long solenoid has current I flowing through it, also denote N as the turns per unit length. Take its axis to be the z-axis, by symmetry the only component of the magnetic field inside is Bz. Find the magnetic field at the center of the solenoid (on the axis). Also, find the magnetic field at the ends of the solenoid. 2. Relevant equations Ampere's Law 3. The attempt at a solution For the first part, since the solenoid is long we can approximate the magnetic field inside to be uniform and is given by Bz=μoNI, so we can say that the magnetic field at the center is also μoNI. I'm not sure if my argument is correct but based on my understanding, from the uniformity of the B field inside, it should be the same everywhere inside. Can anyone kindly tell me if this is correct? Any suggestions and insights? For the second part I don't have any idea on how to start.