Electromagnetic Wave

This simulation draws a light wave as an electric field and a magnetic field that rise and fall together while travelling in a straight line. The wavelength slider covers the visible spectrum from 380 to 750 nm and the wave takes on the matching colour. Students can change the amplitude and show or hide each field. Readouts give wavelength, frequency, the speed found from c = f times lambda, and photon energy. It works well for teaching that light is an electromagnetic wave and that colour is set by wavelength.

• Slide Wavelength from 380 to 750 nm and watch the colour and the Frequency readout change.
• Check the Speed c = f lambda readout at several wavelengths and note that it stays the same.
• Turn off Show B field, then Show E field, to look at each field on its own.
• Raise Amplitude and notice the wave gets taller but the wavelength stays the same.
• Compare Photon energy for violet and red light and say which has more energy.

1. 1Describe light as an electric and magnetic field oscillating at right angles.
2. 2Use c = f x lambda to relate frequency and wavelength.
3. 3Explain that all wavelengths travel at the same speed in a vacuum.
4. 4Compare the photon energy of red and violet light.

Questions teachers ask