Chapter 19 - Magnetism - Learning Path Questions and Exercises - Exercises - Page 688: 13

(d) downward

We can use right-hand force rules to determine the direction of magnetic force. Earth's magnetic field at the equator will be pointing south, thus right hands palm should be facing south and the fingers should align with the direction of current. west. Thus the force will be in the direction of the thumb, i.e. downward.