MotionLab

Magnetic Force Calculator

Moving charges feel a sideways push in a magnetic field — the force that makes electric motors spin.

The force is always perpendicular

Unlike gravity or electric forces, the magnetic force is always perpendicular to both the velocity and the magnetic field — this is why it can change a particle's direction but never its speed, causing charged particles to move in circles (or spirals) in uniform magnetic fields.

The sin(θ) factor is crucial

When a charge moves parallel to the field lines (θ = 0° or 180°), the magnetic force is zero — it only feels the full force when moving perpendicular (θ = 90°). This angle dependence is why particle accelerators and mass spectrometers are carefully designed to control the orientation of particles relative to the field.