Read the passage about an investigation.

Question

A student is performing an investigation in which she wraps a current-carrying wire around an iron rod. She places the north pole of a bar magnet near the top of the rod. The magnet moves away from the rod. The student claims that a field exists between the rod and the magnet.
Which argument BEST supports her claim?

The current in the wire has created a magnetic field with its north pole at the top of the rod
The current in the wire has created a magnetic field with its south pole at the top of the rod
The current in the wire has created a gravitational field with its north pole at the top of the rod
The current in the wire has created a gravitational field with its south pole at the top of the rod

Answer 1

The argument that BEST supports the student's claim is:

The current in the wire has created a magnetic field with its north pole at the top of the rod.

This is because the current-carrying wire generates a magnetic field around it, and if the north pole of a bar magnet is repelled (moving away from the rod), that suggests a magnetic interaction between the bar magnet and the magnetic field generated by the current in the wire. Since like poles repel, it indicates that the rod has developed a north pole at its top, thereby supporting the claim of a magnetic field existing between the rod and the magnet.