Solenoid
A long helical coil of insulated wire that produces a uniform interior magnetic field when an electric current flows through it.
Governing formula
B = μ₀ n I (where n = N / L)
SI unit
T (Tesla)
In depth
The magnetic field inside an ideal long solenoid is uniform and directed along the central axis, while the external field is nearly zero.
Examples in the real world
Electromechanical solenoid switches operating starter motors, or electronic water valves in washing machines.