To convert an $AC$ generator into a $DC$ generator,

What are the factors on which the magnetic field due to a current carrying solenoid depends?

What is the advantage of the third wire of earth connection in domestic appliances?

Define magnetic field. $A$ compass needle gets deflected when brought near a bar magnet. Why? List three properties of magnetic field lines.

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

$A$ 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?