Charged Particles in a Magnetic Field (Lorentz Force)

Theory

The magnetic force $\vec{F}=q\vec{v}\times \vec{B}$ is always perpendicular to the velocity: it changes direction, not speed. The result is a circle of radius $r=\frac{mv}{|q|B}$ and period $T=\frac{2\pi m}{|q|B}$ (independent of $v$ — the cyclotron principle!).

What to observe

• Opposite charges circle in opposite directions.
• The particle twice as fast draws a circle twice as large in the same time.

Try this

• Select a particle and read the predicted radius in the field readouts.
• Reverse the field (negative B).

Also available in: Partículas carregadas em campo magnético (força de Lorentz) (Português) · Partículas cargadas en un campo magnético (fuerza de Lorentz) (Español)