Força em Fio com Corrente
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
F = BIL sen θ
About this calculator
This calculator determines the magnetic force on a straight current-carrying wire placed in a uniform magnetic field. The force is calculated using the formula F = BIL sin θ, where B is the magnetic field strength, I the current, L the wire length, and θ the angle between the wire and the field. The result is given in newtons, with options to convert to other force units.
The formula derives from the Lorentz force law, which describes the force on moving charges. As current flows through the wire, moving electrons experience a magnetic force, resulting in a net force perpendicular to both the wire and the field. The sine of θ adjusts the force magnitude, maximum when the wire is perpendicular (θ = 90°) and zero when parallel (θ = 0°).
Use this tool in scenarios such as electric motor design, where the force on windings determines torque, or in lab experiments to measure magnetic field strengths. It is also useful for sizing cables in electrical systems exposed to external magnetic fields, such as transmission lines or industrial equipment.
Cautions: ensure the magnetic field is uniform over the wire length, as the formula assumes this condition. Also, the wire must be straight and the current constant. For curved wires or non-uniform fields, you need to integrate the force along the length. Remember that the force is perpendicular to both the wire and the field, with direction given by the right-hand rule.
Frequently asked questions
How do I convert the result to other force units?
The calculator displays the result in newtons. You can manually convert: 1 N = 0.2248 lbf or 0.10197 kgf. Use standard conversion factors.
What happens if the angle θ is 0 degrees?
If θ = 0°, the sine is zero, so the magnetic force is zero. This occurs when the wire is parallel to the magnetic field, with no perpendicular component.
Can I use this calculator for non-straight wires?
No, the formula F = BIL sin θ is valid only for straight wires in a uniform field. For curved wires, you need to integrate the force along the wire.
What is the direction of the magnetic force?
The force is perpendicular to both the wire and the magnetic field. Use the right-hand rule: thumb in current direction, fingers in field direction, palm indicates force.
Does this calculator consider alternating current?
The formula assumes constant direct current. For alternating current, the force varies with time, and the calculated value would be the instantaneous force at a given moment.