Which of the following appliances cannot be connected in a $15\, A$ current line?

The magnetic field produced by a straight current-carrying conductor is in the form of concentric circles.

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

From which of the following cases,will the induced current in the loop not be obtained?

On which principle is electricity generated in a power plant?

$A$ 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?