Question

An equilateral triangular loop is kept near to a current carrying long wire as shown in figure. Under the action of magnetic force alone, the loop

• A. must move along positive or negative X-axis
• B. must move in XY plane and not along X- of Y- axis
• C. does not move
• D. moves but which way we cannot predict

Answer 1

The correct option is A must move along positive or negative X-axis

The magnetic field would be into the plane of the triangle, with magnitude decreasing as gone farther from the the current carrying wire. From symmetry, the magnitudes of $\overrightarrow{F_1}$ and $\overrightarrow{F_2}$ would be same. Thus they would not have any vertical component.

Thus, the triangle would move only in the X-direction.