How does a current-carrying solenoid behave?

State the direction of the magnetic field inside the bar magnet.

If you strike a sharp edge of a metallic knife against the north pole of a bar magnet,it will induce a north pole.

Why do iron filings arrange themselves in a certain pattern around a magnet?

$A$ beam of alpha particles enters a chamber moving along a magnetic field. What is the magnetic force experienced by the beam?

The figure shows a long solenoid,a cylindrical coil of a number of turns of insulated copper wire,connected to a battery through an ammeter $A$ and a rheostat $Rh$.
$(i)$ Which end of the solenoid is a $N$-pole and which end is a $S$-pole?
$(ii)$ Draw the magnetic field lines inside the solenoid and indicate their directions. Are magnetic field lines closed?
$(iii)$ How can you increase the strength of the magnetic field inside the solenoid? Give two methods.