🧲 Magnetic Force Calculator
Choose a moving charge or a current-carrying wire, enter the values, and get the magnetic force — with the angle to the field.
Magnetic force
8e-14 N
A magnetic field pushes on moving charge. For a single charge the Lorentz force is F = q·v·B·sinθ; for a current-carrying wire it's F = B·I·L·sinθ. The force is greatest when the motion (or current) is perpendicular to the field (θ = 90°) and zero when parallel. 🔒 In your browser.
How the magnetic force calculator works
A magnetic field exerts a force on moving charge. For a single charge, the Lorentz force is F = q·v·B·sinθ, where q is the charge, v its speed, B the field strength and θ the angle between the velocity and the field. For a straight current-carrying wire, the force is F = B·I·L·sinθ, with I the current and L the length in the field. Both are maximal when the motion or current is perpendicular to the field (θ = 90°) and zero when parallel.
The force is always perpendicular to both the velocity (or current) and the field — its direction follows the right-hand rule; this tool gives the magnitude. On a moving charge the magnetic force does no work (it only bends the path into a circle or helix), which is the basis of mass spectrometers and cyclotrons.
Frequently asked questions
How do you calculate the magnetic force on a moving charge?
F = q·v·B·sinθ, where q is the charge in coulombs, v the speed, B the magnetic field in tesla and θ the angle between v and B. A charge moving along the field (θ = 0) feels no force; perpendicular (θ = 90°) feels the most.
What is the force on a current-carrying wire in a magnetic field?
F = B·I·L·sinθ, where I is the current, L the length of wire in the field, B the field strength and θ the angle between the wire and the field. This is the force that turns electric motors.
When is the magnetic force zero?
When the motion (or current) is parallel to the field, because sin 0° = 0. There's no magnetic force on a charge moving straight along the field lines, or on a wire aligned with the field.
What is the Lorentz force?
The force on a charged particle from electric and magnetic fields. Its magnetic part is F = qvB·sinθ, always perpendicular to the velocity — so it curves the particle's path without changing its speed.
Why does the magnetic force do no work on a charge?
Because it acts perpendicular to the velocity, so there's no force component along the direction of motion. It changes the direction (bending the path into a circle or helix) but not the speed or kinetic energy.