What is the nature of the magnetic field lines passing through the center of a current-carrying circular loop?

For the circular coil carrying current shown alongside,draw magnetic field lines. Decide which of its face behaves as north pole and which face as south pole. Give reason to justify your answer.

$A$ student performs an experiment to study the magnetic effect of current around a current-carrying straight conductor with the help of a magnetic compass.
He reports that:
$(i)$ the degree of deflection of the magnetic compass increases when the compass is moved away from the conductor.
$(ii)$ the degree of deflection of the magnetic compass increases when the current through the conductor is increased.
Which of the above observations of the student appears to be wrong and why?

The flow of a current in a circular loop of a wire creates a magnetic field at its centre. How can the existence of this field be detected? State the rule which helps to predict the direction of this magnetic field.

Which of the following correctly describes the magnetic field near a long straight wire?

$A$ 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?