How is the magnetic field produced in a solenoid used?

In the arrangement shown in the figure,there are two coils wound on a non-conducting cylindrical rod. Initially,the key is not inserted. Then the key is inserted and later removed. Then

With the help of a labelled circuit diagram,illustrate the pattern of field lines of the magnetic field around a current-carrying straight long conducting wire. How is the Right-Hand Thumb Rule useful to find the direction of the magnetic field associated with a current-carrying conductor?

$A$ current through a horizontal power line flows in east to west direction. What is the direction of magnetic field at a point directly below it and a point directly above it?

Explain with the help of a labelled diagram the distribution of magnetic field due to a current through a circular loop. Why is it that if a current-carrying coil has $n$ turns,the field produced at any point is $n$ times as large as that produced by a single turn?

$A$ magnetic compass shows a deflection when placed near a current-carrying wire. How will the deflection of the compass be affected if the current in the wire is increased? Support your answer with a reason.