What does the direction of the thumb indicate in the right-hand thumb rule?

$A$ student performs an experiment to study the magnetic effect of current around a current-carrying straight conductor. He reports that:
$(i)$ The direction of deflection of the north pole of a compass needle kept at a given point near the conductor remains unaffected even when the terminals of the battery sending current in the wire are interchanged.
$(ii)$ For a given battery,the degree of deflection of a $N$-pole decreases when the compass is kept at a point farther away from the conductor.
Which of the above observations of the student is incorrect and why?

$A$ coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is withdrawn from inside the coil?

Name any three factors on which the magnitude of the magnetic field due to a solenoid depends.

The direction of the magnetic field produced by a current-carrying straight wire depends on which of the following?

The magnetic field produced by a current flowing through a straight conductor is inversely proportional to the $........$.