Question

a long wire carries a current toward the east in a magnetic field that is directed vertically downward, perpendicular to the surface of earth. what is the direction of the magnetic force on the wire? west north east south no magnetic force is exerted on the wire.

Explanation:

Step1: Apply right - hand rule

Point the thumb of your right - hand in the direction of the current (east) and the fingers in the direction of the magnetic field (vertically downward). The palm will then point in the direction of the magnetic force.
According to the right - hand rule for the magnetic force on a current - carrying wire $F = IL\times B$, the magnetic force is directed south.

Answer:

south