A 27.0-cm long solenoid 1.25 cm in diameter is to produce a field of 0.215 T at its center. How much current should the solenoid carry if it has 900 turns of the wire?
B = μIN / l
The Attempt at a Solution
Why am I given the diameter plus the length? Everything else is obvious except this concept. I thought l would equal = 0.27 m. Should I add 0.625 + 0.27 m because the magnetic field is produced at the center?