(N/A) When a magnetic needle is brought near a current-carrying conductor,it deflects because the magnetic field produced by the current-carrying conductor exerts a magnetic force on the needle.
The direction of the force experienced by a current-carrying conductor placed in a magnetic field is determined by Fleming's Left-Hand Rule. According to this rule,stretch the thumb,forefinger,and middle finger of your left hand such that they are mutually perpendicular to each other. If the forefinger points in the direction of the magnetic field and the middle finger points in the direction of the current,then the thumb will point in the direction of the force (or motion) experienced by the conductor.