Visualize propagation and wavelength relationship
A wave is a disturbance that carries energy from one place to another without moving actual matter over long distances. In this simulation, you see a Transverse Wave—like a ripple on a pond or a wave on a string. The particles move up and down, but the energy of the wave travels from left to right.
These two properties are like a seesaw. If you increase the Frequency (how many waves pass by per second), the Wavelength (the distance between peaks) must get shorter. Try sliding the frequency up: you'll see the waves bunching together. Slide it down, and they stretch out.
The relationship between speed ($v$), frequency ($f$), and wavelength ($\lambda$) is one of the most important equations in physics: $v = f \times \lambda$. In this simulator, the speed is locked at 300 m/s. This means that if you know the frequency, you can always calculate exactly how long the wave is!
While this simulation looks like a simple line, the same math applies to almost everything in the universe. Sound waves in the air, light waves from the sun, and even the "matter waves" described in quantum mechanics all follow these fundamental rules of oscillation and propagation.