Question

the wire is then connected to a battery so that a current flows down the wire. how will the compasses point once the current is flowing?

Explanation:

Step1: Apply right - hand rule

Use right - hand rule for magnetic field around current - carrying wire. Curl fingers of right hand in direction of current (down the wire), thumb points in direction of magnetic field lines around wire.

Step2: Determine compass direction

Compass needle points in direction of magnetic field. Magnetic field lines are circular around wire. For compasses around wire, they will point in a circular pattern around the wire.

Answer:

The compasses will point in a circular pattern around the wire, with the direction determined by the right - hand rule for the magnetic field of a current - carrying wire.