Force on Current-Carrying Conductor in Magnetic Field

Steps:

• Assume uniform magnetic field downward between N (top) and S (bottom) poles; coil horizontal with current clockwise (W to X rightward, X to Y forward, Y to Z leftward, Z to W backward).
• For side WX (current rightward), field downward: Fleming's left-hand rule gives force upward (thumb up, index down, middle right).
• For side YZ (current leftward, parallel to WX but opposite), force downward.
• Sides XY and ZW have current parallel to field, so no force (sinθ=0).

Why A is correct:

• Fleming's left-hand rule confirms upward force on WX as current perpendicular to downward field produces vertical force opposing field direction.

Why the others are wrong:

• B: YZ experiences downward force, not outward (perpendicular sides have no force).
• C: YZ experiences downward force, not inward.
• D: ZW has current parallel to field, so zero force, not downward.

Final answer: A