Ondes électromagnétiques
An electromagnetic wave is two waves travelling as one, at right angles to each other and to their direction of travel. This simulation draws the electric and magnetic field vectors in 3D as the wave propagates.
Comment utiliser cette simulation
- Rotate the 3D view of the field vectors
- Change the frequency and move across the spectrum
- Show the electric and magnetic components separately
Ce qu’il faut observer
- The two fields peak and vanish together, in phase with each other
- E, B and the propagation direction are mutually perpendicular
- Every frequency travels at the same speed in vacuum, from radio to gamma
La physique derrière
A changing electric field generates a magnetic field and vice versa, so the two sustain each other and propagate without any medium at speed c = 1/√(μ₀ε₀), about 3×10⁸ m/s. The fields oscillate in phase, mutually perpendicular, and perpendicular to the direction of travel — which is why light is a transverse wave and can be polarised.