# Illustration Spiral motion of an electron in a magnetic field

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An electron moves with velocity $$v$$ at an angle to the homogeneous magnetic field $$B$$. The electron has a velocity component perpendicular $$v_\perp$$ and parallel $$v_{||}$$ to the magnetic field. The perpendicular velocity component causes a circular motion with radius $$r$$ and the parallel velocity component causes a motion along magnetic field lines. The total motion is a spiral path.

The spiral path has the pitch $$h$$ - this is the distance the electron travels in the magnetic field direction during one period.