**Charged Particle in a Uniform Electric and Magnetic Field**

When a charged particle enters a region containing uniform electric and magnetic fields, its motion can be affected by these fields. If the charged particle passes through the region without any deviation, it implies that the velocity of the charged particle must have a specific magnitude and direction to counteract the effects of the electric and magnetic fields.

**Electric Field Effect**
- The electric field exerts a force on a charged particle, given by the equation F = qE, where F is the force, q is the charge of the particle, and E is the electric field.
- The force due to the electric field is always in the direction of the field lines.
- If the charged particle passes through the region without deviation, it means that the force due to the electric field must be balanced by other forces acting on the particle.

**Magnetic Field Effect**
- The magnetic field exerts a force on a charged particle moving through it, given by the equation F = qvB, where v is the velocity of the particle and B is the magnetic field.
- The force due to the magnetic field is perpendicular to both the velocity of the particle and the magnetic field direction, following the right-hand rule.
- If the charged particle passes through the region without deviation, it means that the force due to the magnetic field must be balanced by other forces acting on the particle.

**Velocity of the Charged Particle**
- To pass through the region without deviation, the charged particle must have a specific velocity that balances the forces due to the electric and magnetic fields.
- The electric field force can be balanced by an equal and opposite force due to another electric field or a gravitational force, for example.
- The magnetic field force can be balanced by an equal and opposite force due to another magnetic field or other forces such as friction.
- The magnitude and direction of the velocity of the charged particle depend on the magnitudes and directions of the electric and magnetic fields, as well as the other forces present in the region.
- The specific velocity required for the charged particle to pass through the region without deviation can be determined by analyzing the forces acting on the particle.

In summary, for a charged particle to pass through a region containing uniform electric and magnetic fields without deviation, the velocity of the particle must be carefully chosen to balance the forces due to these fields. The specific magnitude and direction of the velocity depend on the magnitudes and directions of the electric and magnetic fields, as well as the other forces present in the region.

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