Final answer:
A charged particle experiences a magnetic force perpendicular to its velocity and the magnetic field. The particle follows a curved path called circular motion.
Step-by-step explanation:
When a charged particle moves perpendicular to a uniform magnetic field, it experiences a magnetic force that is perpendicular to both its velocity and the magnetic field. This force causes the particle to follow a curved path known as circular motion.
Using the right-hand rule, we can determine the direction of the magnetic force on the particle. If the velocity is pointed towards the magnetic field lines (into the page), the force will be directed clockwise. If the velocity is opposite to the magnetic field lines (out of the page), the force will be directed counterclockwise.