Answer:
Step-by-step explanation:
To determine the direction of the magnetic field in this region, we can use the right-hand rule for magnetic forces.
If we point our right thumb in the direction of the particle's velocity (in the +x direction) and our right fingers in the direction of the magnetic force (in the -y direction), then the direction of the magnetic field will be perpendicular to both the velocity and force vectors, and will be in the +z direction.
Here's a labelled diagram to help visualize this:
z
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|_______________y
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/
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x
In this diagram, the particle is moving in the +x direction (out of the page) and experiences a magnetic force in the -y direction (towards the bottom of the page). Therefore, the magnetic field must be in the +z direction (upwards on the page), perpendicular to both the velocity and force vectors.
Note: This assumes that the particle is negatively charged, which means that its velocity vector points in the opposite direction to the direction of the electric field. If the particle were positively charged, the direction of the magnetic field would be in the -z direction (downwards on the page).