1.

The shape of the magnetic field from a solenoid is essentially the same as the magnetic field from a bar magnet that has the same dimensions as the solenoid. Even in a bar magnet, the magnetic field is produced by a current, which is a set of flowing charges. In a bar magnet, what are the charges that produce the magnetic field? You’ll probably need to do some research on this question – how do the charges act collectively to generate the field? Do they actually flow around the bar magnet?

2.

The textbook states that the magnetic field inside an infinitely long solenoid is given by mon I, where n is the number of turns per unit length. In this simulation n is 1/the distance between the turns. For a range of solenoid geometries, compare the value of the magnetic field obtained using the equation to the magnetic field obtained by the simulation. The two values can be significantly different, depending on the geometry of the solenoid. This tells you something about the validity of the equation – when does the equation B = mon I apply?