Question

three parallel wires carry the same current in the same direction and are in the same uniform magnetic field. wire 1 consists of moving electrons, wire 2 consists of moving protons, and wire 3 consists of both electrons and protons, moving in opposite directions. which of the following is true? the magnetic forces on wires 2 and 3 are in the same direction, and the magnetic force on wire 1 is in the opposite direction. the magnetic - forces on the three wires are all in the same direction. no two magnetic forces are in the same direction. the magnetic forces on wires 1 and 2 are in the same direction, and the magnetic force on wire 3 is in the opposite direction. the magnetic forces on wires 1 and 3 are in the same direction, and the magnetic force on wire 2 is in the opposite direction.

Explanation:

Step1: Recall magnetic - force on current - carrying wires

The magnetic force on a current - carrying wire in a magnetic field is given by $\vec{F}=I\vec{L}\times\vec{B}$, where $I$ is the current, $\vec{L}$ is the length vector of the wire, and $\vec{B}$ is the magnetic field. When two parallel current - carrying wires are in a magnetic field, the direction of the magnetic force on them depends on the direction of the current and the magnetic field. If two wires carry current in the same direction, the magnetic forces on them due to the external magnetic field will be in the same direction.

Step2: Analyze the given situation

Wires 1, 2, and 3 carry the same current in the same direction in a uniform magnetic field. According to the right - hand rule for the magnetic force on a current - carrying wire ($\vec{F}=I\vec{L}\times\vec{B}$), the magnetic forces on the three wires are all in the same direction.

Answer:

The magnetic forces on the three wires are all in the same direction.