READ: Wavelength and Frequency
3. Amplitude
Wave Amplitude
Wave amplitude is the maximum distance the particles of the medium move from their resting positions when a wave passes through. The resting position of a particle is where the particle would be if the wave had not traveled through the material. The crest is the highest point of a wave and the trough is the lowest point. Wavelength is the distance from one point on a wave to the same point on the next wave. In the picture it shows a wavelength from the trough to the trough of the next wave. A wavelength however could also be measured from the crest to crest.
Energy and Amplitude
The greater the amplitude the “stronger” the wave. The opposite is also true. The exact meaning of "strength" depends on the type of wave. For example, a sound wave with a large amplitude is a loud sound.
Below are three different sketches of waves.What do you notice that is similar and different about each of the waves in the sketches?
- Describe the similarities and differences between the waves using the words amplitude and energy.
- Which wave has more energy?
- Which wave has less?
- How do you know?
A student wanted to use a rope as a model to show that waves can have different amplitudes and wavelengths. The student tied a rope to a tree and then moved the rope up and down at two different speeds.
The faster you move the rope up and down, the more energy that is being transferred to the rope therefore amplitude is higher.