Electromagnetic wave: interactive electric and magnetic fields

The relationship to understand

E(x,t)=E₀ cos(ωt−kx), B=E/c, λ=c/ν and I=ε₀cE₀²/2.

Try it and interpret

At 50 MHz in vacuum, the wavelength is about 6 m and the period is 20 ns. Advance by one eighth of a period to follow a fixed position, then start the slow-motion animation.

Assumptions and limitations

Linearly polarised plane wave traveling through vacuum. B is drawn at a scale comparable to E; its physical values are reported separately. Two seconds of playback represent one visual period, not the physical duration.

Go further with the course

This page focuses on one concept. The full chapter (French) contains the reasoning, further examples, slides and FAQ. Demonstration values are computed or constructed within the stated model; they are not new research findings.