Three conductors carrying currents are perpendicular to the plane of the drawing. They intersect the plane at three points that lie on a single straight line, with the distances from the middle conductor to the other two being equal. The currents in the outer conductors flow away from the reader, while the current in the middle conductor flows toward the reader. How is the magnetic field vector directed at the point on the straight line that is perpendicular to the straight line passing through the three conductors in the plane of the drawing and is separated from the middle conductor by a distance equal to the distances between that conductor and the outer conductors? All three currents are equal in magnitude.

                

Along four parallel conductors whose sections with the plane of the drawing lie at the vertices of a square there flow four equal currents (the directions of these currents are as follows: those marked with an "$x$" point away from the reader, while those marked with a dot point to the reader. How is the vector of magnetic induction directed at the center of the square?

Two infinitely long parallel conductors carrying currents are directed at right angles to the plane of the drawing. The maximum of magnetic induction is at a point $M$ that lies in the middle between the conductors. The direction of the magnetic induction vector $B$ at this point coincides with the positive direction on the $x$ axis. Determine the direction of the currents flowing in the conductors and the relationship that exists between these currents.

Two infinitely long parallel conductors carrying currents are directed at right angles to the plane of the drawing. The magnetic induction at a point $M$ that lies in the middle between the conductors is zero. To the right of this point, the magnetic induction vector points upward, at right angles to the $x$ axis. Find the direction of the currents flowing in the conductors, the direction of the magnetic induction vector to the left of point $M$, the relationship between the currents, and the point on the $x$ axis at which the magnetic induction is maximal. The distance between the conductors is $a$.

A current flows clockwise in a flat square loop. In the plane of the loop there lies an infinitely long straight conductor carrying a current whose direction is designated by the arrow in the figure. How will the loop move in the magnetic field created by the current flowing in the straight conductor, and how will the shape of the loop change as a result of the action of this field?

A conducting loop carrying a current is placed in a nonuniform magnetic field. How will it move as a result of the action of this field?

A direct current (constant in magnitude and direction) flows in a contour made from soft wire. What shape does this contour tend to acquire as a result of the action of the magnetic field created by the current?

At a small distance from a solenoid carrying a current there is placed a contour with a current in such a manner that the solenoid's axis lies in the plane of the contour. The directions of the currents in solenoid and contour are shown by arrows. How does the contour move? How will it move if the current in it flows in the direction opposite to the one shown in the figure?