Here the magnetic field of a two-turn solenoid is calculated* on a set of cartesian grid points located at the base of each plotted arrow. As you can see, a cluster of near-parallel magnetic field lines is created when a current runs through the coil. You can reorient the model by dragging the mouse over it for a clearer look at its three-dimensional structure. Puzzler #1: Which way is the current in this solenoid flowing, i.e. is current moving in the direction of the larger magnetic field arrows, or vice versa?
* (by integrating Biot-Savart's dB=μoIds×r/r3 over the wire's length)