Electrodynamics
Electromagnetic waves in vacuum
Observe that E, B, and propagation are mutually perpendicular, E and B oscillate in phase, and their amplitudes satisfy E₀/B₀ = c in vacuum.
Equipment
- Transverse field display with adjustable frequency and field amplitude
- Vacuum propagation axis and wavelength scale
- Phase and amplitude readouts for E and B
Procedure
Set the propagation conditions
In an experimental analogue, launch a narrow-band source into a vacuum chamber or use a calibrated waveguide. Set the frequency and record it before measuring wavelength between successive equal-phase points.
Compare the field directions
At a fixed position, compare the E and B arrows with the propagation axis. Rotate the polarization plane and verify that both field vectors remain transverse to the direction of travel.
Test frequency, wavelength, and phase
Change frequency while keeping the vacuum medium unchanged, measure the new wavelength, and calculate fλ. Compare it with c. Read E and B at the same position and confirm their maxima and zero crossings coincide; check the amplitude ratio E₀/B₀.