Question

For a charged particle moving at an angle θ to a magnetic field \[\vec B\] (0° < θ < 90°), the parallel component of velocity \[v_\parallel = v \cos\theta\]:

Options

• Causes linear motion along \[\vec B\] that remains unchanged

• Is reduced to zero by the magnetic force

• Causes circular motion of the particle

• Causes the particle to spiral inward toward the field lines

Answer 1

The velocity component parallel to \[\vec B\], given by \[v_\parallel = v \cos\theta\], causes linear motion that remains unchanged because the magnetic force acts perpendicular to \[\vec B\] and cannot affect the motion parallel to the field. The combination of circular and linear motion produces a helical path.