Objective
Watch an electromagnetic wave roll by and see the electric and magnetic fields oscillating in lockstep, perpendicular to each other and to the direction of travel.
The idea
Light, radio, WiFi - all are EM waves. An electric field and a magnetic field swing together, at right angles to each other, carrying energy across empty space at light speed.
Try this
- 1Change the frequency and watch the wavelength shrink.
- 2Compare a radio-wave setting with a light-wave setting.
- 3Pause the wave and inspect one point: E and B in phase.
- 4Raise the amplitude and feel the energy jump.
Watch for
- E and B are perpendicular to each other and to the direction of travel.
- They rise and fall in phase - both peak together.
- Wavelength and frequency trade off: c = lambda x f.
- Amplitude squared measures the energy the wave carries.