What is the pattern of field lines inside a solenoid? What do they indicate?

$A$ straight conductor passes vertically through a cardboard sprinkled with iron filings. Show the setting of iron filings when a weak current is passed in the downward direction and then the cardboard is gently tapped. Draw arrows to represent the direction of magnetic field lines.
What changes occur if,
$(i)$ the strength of current is increased?
$(ii)$ the single conductor is replaced by several parallel conductors each carrying same current flowing in the same direction?

What are the safety measures to be taken while dealing with household electricity?

$A$ soft iron bar is introduced inside a current-carrying solenoid. The magnetic field inside the solenoid:

$A$ current $I$ passes through a circular loop $C$ and a solenoid $AB$ as shown below:
$(i)$ What is the polarity of: $(a)$ the face of the loop you are looking at? $(b)$ the end $B$ of the solenoid?
$(ii)$ What is the direction of the magnetic field at the centre of the loop?

Appliances with higher power ratings are connected to which ampere line (in $A$)?