Two loops carry equal currents I in the same direction. They are held in the positions shown in the figure and project above and below the plane of the paper. The point P lies exactly halfway between them on the line that joins their centers. The centers of the loops and the point P lie in the plane of the paper. Which one of the figures below shows the position of a compass needle if the compass were placed in the plane of the paper at P?

Question

Quizplus · Accepted Answer

According to the right-hand rule, a current-carrying loop generates a magnetic field that points perpendicular to the plane of the loop in the direction determined by the direction of the current. As both loops carry equal currents in the same direction, they produce the same magnetic field at point P in opposite directions. Therefore, the magnetic field at point P is zero. A compass needle will align with the magnetic field at its location, so it will not show any deflection if placed at point P. Hence, the correct answer is the figure showing a compass needle pointing to the north, indicating no magnetic field at point P. This is represented by option D.

Two Loops Carry Equal Currents I in the Same Direction