Final answer:
The amplitude of a longitudinal wave is measured by the maximum displacement from the equilibrium position, not by counting peaks or measuring wavelength. Units for amplitude are typically in meters or centimeters.
Step-by-step explanation:
To measure the amplitude of a longitudinal wave, you would look at the maximum displacement from the equilibrium position. In a longitudinal wave, the amplitude is not measured by counting peaks (like in a transverse wave), but rather by measuring how far the particles of the medium move away from their rest position (equilibrium) during a wave cycle. The equilibrium position is typically depicted in diagrams as a dotted line or the position where particles of the medium would be if no wave was passing through. The amplitude could be the distance from this equilibrium line to the position of maximum compression or rarefaction.
For a symmetrical wave, the amplitude is the same distance above (in case of a compression) and below (in a rarefaction) this equilibrium line. This is also known as the peak to trough distance in transverse waves. However, for measuring a longitudinal wave, you can think of it as the distance from the midpoint of the wave cycle (equilibrium) to the point of maximum compression or rarefaction. The units for amplitude would typically be in meters or centimeters, depending on the scale of the wave.
Regarding the other options provided:
- Measuring wavelength - This is a different concept, referring to the distance between two similar points in consecutive waves, such as from compression to compression or rarefaction to rarefaction in a longitudinal wave.
- Calculating frequency - Frequency is about how many waves pass a point per second and is not a measurement of amplitude.
The correct answer to measure the amplitude of a longitudinal wave is (c) Measuring displacement from equilibrium.