Fluxo Magnético
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
Φ = BA cos θ
About this calculator
The magnetic flux calculator determines the amount of magnetic field passing through a surface using the formula Φ = B·A·cos θ. Magnetic flux (Φ) is the product of the magnetic field (B), the area of the surface (A), and the cosine of the angle (θ) between the field and the surface normal. This quantity is essential for understanding phenomena like electromagnetic induction, where changes in flux induce electromotive force.
To use the calculator, enter the magnetic field (in tesla), area (in square meters), and angle (in degrees or radians). The result is the magnetic flux in webers. For example, a field of 0.5 T perpendicular (θ=0°) to an area of 2 m² yields a flux of 1 Wb. This tool is useful for students and professionals in engineering and physics working with electromagnetism.
Common use cases include calculating flux in coils, transformers, and generators. When designing a transformer, for instance, the magnetic flux in the core determines the induced voltage. It is also used in magnetic field sensors and laboratory experiments. The calculator simplifies these calculations, avoiding manual errors.
Important precautions: ensure units are consistent (tesla, m²). The angle must be between the field and the surface perpendicular, not the surface itself. For non-flat surfaces, total flux is the integral of the field over the area. Also, remember that flux can be negative if the field points opposite to the normal direction.
Frequently asked questions
What does negative magnetic flux mean?
Negative magnetic flux indicates that the magnetic field points opposite to the surface normal direction. The sign is important for induction calculations, as a change in flux (from positive to negative) induces an electromotive force.
How do I convert degrees to radians for the angle?
To convert degrees to radians, multiply the angle in degrees by π/180. The calculator accepts both units, but make sure to select the correct option.
Can I use the calculator for curved surfaces?
The calculator is for flat surfaces. For curved surfaces, total flux is the integral of the field over the area, which can be approximated by dividing the surface into small flat areas.
What is the difference between magnetic flux and magnetic field?
Magnetic field (B) is a vector quantity describing the force per unit current. Magnetic flux (Φ) is the amount of field passing through an area, depending on orientation.
What is a weber?
Weber (Wb) is the SI unit of magnetic flux. One weber equals one tesla times square meter (1 Wb = 1 T·m²).