Physics Waves: Frequency & Wavelength FREE Science Lesson

Summary

The lesson uses familiar water waves to explain concepts that also apply to sound and light waves.

• Wavelength (λ): The distance between successive crests or successive troughs.
• Wave speed (v): How fast the wave travels. In the boat example, the wave moves horizontally while the boat moves up and down.
• Amplitude (A): The wave’s height relative to the calm water level. Greater amplitude is associated with a more energetic source.
• Frequency (f): The number of waves produced or passing a point each second. Frequency is measured in hertz (Hz); 1 Hz means one wave per second.

The boat’s up-and-down motion illustrates that the medium—the water, along with the boat floating on it—does not travel along with the wave. The lesson also introduces simple harmonic motion, a repeating motion in which an object moves fastest around the middle of its cycle. A pendulum is another example.

Increasing the source’s frequency makes the waves closer together, shortening their wavelength. In the demonstration, frequency and wavelength are inversely related: as one increases, the other decreases. A later video will connect wave speed, wavelength, frequency, and amplitude mathematically using the wave equation.

Speakers and Sources Featured

• Off-screen narrator: Presents the lesson and describes the water-wave, boat, and pendulum examples.
• Heinrich Hertz: Mentioned as the scientist who proved the existence of electromagnetic waves; he is not a speaker in the video.