Magnetic Flux Calculator
Calculate the magnetic flux through a surface from the magnetic field, area, and angle between them.
Uses Φ = B·A·cos(θ).
Magnetic Flux
Magnetic flux measures how much magnetic field passes through a given surface:
Φ = B × A × cos(θ)
Where:
- Φ = Magnetic flux (webers, Wb)
- B = Magnetic flux density (Tesla, T)
- A = Area of the surface (m²)
- θ = Angle between the magnetic field vector B and the surface normal
Why magnetic flux matters — Faraday’s Law:
A changing magnetic flux induces an EMF (voltage) in a conductor: EMF = −N × ΔΦ/Δt
This is the principle behind:
- Electric generators (rotating coil changes flux)
- Transformers (alternating current changes flux)
- Induction stoves (changing flux heats the pot)
- Metal detectors (eddy currents from changing flux)
Understanding the angle θ:
- θ = 0°: Field is perpendicular to surface → maximum flux = BA
- θ = 90°: Field is parallel to surface → zero flux (field “skims” the surface)
- A coil rotating in a motor/generator has continuously changing θ, creating AC electricity
Unit: Weber (Wb) 1 Wb = 1 T·m² = 1 V·s
This unit honors German physicist Wilhelm Eduard Weber who pioneered the study of electromagnetism in the 19th century.