A long, straight, current-carrying wire runs from north to south. a. A compass needle placed above the wire points with its north pole toward the east. In What direction is the current flowing
b. If a compass is put underneath the wire, in which direction will the compass needle point?

a. The current is flowing from South to North. So, the current flows in the North direction

b. West

Explanation:

a. A compass needle placed above the wire points with its north pole toward the east. In What direction is the current flowing?

Using Maxwell's corkscrew rule, with the thumb of the right hand pointing in the direction of the current and the closed fingers pointing in the direction of the magnetic field.

Since the compass is placed above the wire and points east, the direction of the magnetic field at that point is east.

Since the magnetic field is tangential to the circular path around the wire, to produce an eastward magnetic field above the wire, the current must go from South to North. So, the current flows in the North direction.

b. If a compass is put underneath the wire, in which direction will the compass needle point?

If the compass is put underneath the wire, using Maxwell's corkscrew rule, since the current points northward, and the magnetic field is tangential to the circular path around the wire, the magnetic field below the wire points west.

So, the direction of the compass needle when the compass is put beneath the wire is west.

your answer is c! hope this : )