Questions: The diagram provided shows a long, straight wire carrying current i within a region of uniform magnetic field. The magnetic force experienced by the wire is also indicated in the diagram, but the magnetic field's direction is not shown. Given the information in the diagram, what must the direction of the magnetic field be? into the plane of the figure out of the plane of the figure downward upward None of the choices are correct

Solution Steps

The magnetic force on a current-carrying wire is given by $\vec{F} = i\vec{L} \times \vec{B}$, where $\vec{F}$ is the magnetic force, $i$ is the current, $\vec{L}$ is the length vector of the wire in the direction of the current, and $\vec{B}$ is the magnetic field. We can use the right-hand rule to determine the direction of the magnetic field.

Point your index finger in the direction of the current (to the right) and your thumb in the direction of the force (upward).

Your middle finger will point into the plane of the figure, which represents the direction of the magnetic field.

Final Answer: The magnetic field must be directed into the plane of the figure.