A uniform magnetic field in the positive y direction acts on a positively charged particle moving in the positive x direction. In what direction does the force act on particle?

Two vectors, v₁ and v₂, each with magnitude of 10, act in the x-y plane, at an angle of 30^o, as shown below. What is the magnitude and direction of the cross product v₁×v₂?

A uniform electric field of 10 dynes/esu acts in the positive x direction, while a uniform magnetic field of 20 gauss acts in the positive y direction. A particle of charge q and velocity of .5c moves in the positive z direction. What is the net force on the particle?

A charged particle moving perpendicular to a uniform magnetic field always experiences a net force perpendicular to its motion, similar to the kind of force experienced by particles moving in uniform circular motion. The magnetic field can actually cause the particle to move in a complete circle. Express the radius of this circle in terms of the charge, mass and velocity of the particle, and the magnitude of the magnetic field.