Magnetic force on charged particle in a magnetic field

Question: Describe the magnetic force on the particle if it is at rest; it moves along  the direction of the magnetic field; it moves opposite the direction of the magnetic field; and if its at right angle with the direction of the magnetic field.
Answer:

1. In a magnetic field B, a particle of charge q and velocit v experiences a force,
F = q(v X B)
If v = 0, the F = 0 and hence the particle experiences no force.
(Here, bold letters represent vectors)
2. if the particle moves in the direction of the field then F=qvBsin(0) = 0 again particle does not experience any force when it move parallel to the magnetic field.
3. Again F=0 for the case when particle moves in a direction opposite to the field as 
F=qvBsin(180) = 0 since the angle between and is 180 degree.
4. In case and are both perpendicular to each other then charged particle will follow the circular path .

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